stl_algo.h source code [include/c++/13.2.1/bits/stl_algo.h]

1	// Algorithm implementation -- C++ --
2
3	// Copyright (C) 2001-2023 Free Software Foundation, Inc.
4	//
5	// This file is part of the GNU ISO C++ Library. This library is free
6	// software; you can redistribute it and/or modify it under the
7	// terms of the GNU General Public License as published by the
8	// Free Software Foundation; either version 3, or (at your option)
9	// any later version.
10
11	// This library is distributed in the hope that it will be useful,
12	// but WITHOUT ANY WARRANTY; without even the implied warranty of
13	// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14	// GNU General Public License for more details.
15
16	// Under Section 7 of GPL version 3, you are granted additional
17	// permissions described in the GCC Runtime Library Exception, version
18	// 3.1, as published by the Free Software Foundation.
19
20	// You should have received a copy of the GNU General Public License and
21	// a copy of the GCC Runtime Library Exception along with this program;
22	// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23	// <http://www.gnu.org/licenses/>.
24
25	/*
26	*
27	* Copyright (c) 1994
28	* Hewlett-Packard Company
29	*
30	* Permission to use, copy, modify, distribute and sell this software
31	* and its documentation for any purpose is hereby granted without fee,
32	* provided that the above copyright notice appear in all copies and
33	* that both that copyright notice and this permission notice appear
34	* in supporting documentation. Hewlett-Packard Company makes no
35	* representations about the suitability of this software for any
36	* purpose. It is provided "as is" without express or implied warranty.
37	*
38	*
39	* Copyright (c) 1996
40	* Silicon Graphics Computer Systems, Inc.
41	*
42	* Permission to use, copy, modify, distribute and sell this software
43	* and its documentation for any purpose is hereby granted without fee,
44	* provided that the above copyright notice appear in all copies and
45	* that both that copyright notice and this permission notice appear
46	* in supporting documentation. Silicon Graphics makes no
47	* representations about the suitability of this software for any
48	* purpose. It is provided "as is" without express or implied warranty.
49	*/
50
51	/* @file bits/stl_algo.h*
52	* This is an internal header file, included by other library headers.
53	* Do not attempt to use it directly. @headername{algorithm}
54	*/
55
56	#ifndef _STL_ALGO_H
57	#define _STL_ALGO_H 1
58
59	#include <bits/algorithmfwd.h>
60	#include <bits/stl_algobase.h>
61	#include <bits/stl_heap.h>
62	#include <bits/predefined_ops.h>
63
64	#if __cplusplus >= 201103L
65	#include <bits/uniform_int_dist.h>
66	#endif
67
68	#if _GLIBCXX_HOSTED
69	# include <bits/stl_tempbuf.h> // for _Temporary_buffer
70	# if (__cplusplus <= 201103L \|\| _GLIBCXX_USE_DEPRECATED)
71	# include <cstdlib> // for rand
72	# endif
73	#endif
74
75	// See concept_check.h for the __glibcxx__requires macros.*
76
77	namespace std _GLIBCXX_VISIBILITY(default)
78	{
79	_GLIBCXX_BEGIN_NAMESPACE_VERSION
80
81	/// Swaps the median value of __a, __b and __c under __comp to __result
82	template<typename _Iterator, typename _Compare>
83	_GLIBCXX20_CONSTEXPR
84	void
85	__move_median_to_first(_Iterator __result,_Iterator __a, _Iterator __b,
86	_Iterator __c, _Compare __comp)
87	{
88	if (__comp(__a, __b))
89	{
90	if (__comp(__b, __c))
91	std::iter_swap(__result, __b);
92	else if (__comp(__a, __c))
93	std::iter_swap(__result, __c);
94	else
95	std::iter_swap(__result, __a);
96	}
97	else if (__comp(__a, __c))
98	std::iter_swap(__result, __a);
99	else if (__comp(__b, __c))
100	std::iter_swap(__result, __c);
101	else
102	std::iter_swap(__result, __b);
103	}
104
105	/// Provided for stable_partition to use.
106	template<typename _InputIterator, typename _Predicate>
107	_GLIBCXX20_CONSTEXPR
108	inline _InputIterator
109	__find_if_not(_InputIterator __first, _InputIterator __last,
110	_Predicate __pred)
111	{
112	return std::__find_if(__first, __last,
113	__gnu_cxx::__ops::__negate(__pred),
114	std::__iterator_category(__first));
115	}
116
117	/// Like find_if_not(), but uses and updates a count of the
118	/// remaining range length instead of comparing against an end
119	/// iterator.
120	template<typename _InputIterator, typename _Predicate, typename _Distance>
121	_GLIBCXX20_CONSTEXPR
122	_InputIterator
123	__find_if_not_n(_InputIterator __first, _Distance& __len, _Predicate __pred)
124	{
125	for (; __len; --__len, (void) ++__first)
126	if (!__pred(__first))
127	break;
128	return __first;
129	}
130
131	// set_difference
132	// set_intersection
133	// set_symmetric_difference
134	// set_union
135	// for_each
136	// find
137	// find_if
138	// find_first_of
139	// adjacent_find
140	// count
141	// count_if
142	// search
143
144	template<typename _ForwardIterator1, typename _ForwardIterator2,
145	typename _BinaryPredicate>
146	_GLIBCXX20_CONSTEXPR
147	_ForwardIterator1
148	__search(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
149	_ForwardIterator2 __first2, _ForwardIterator2 __last2,
150	_BinaryPredicate __predicate)
151	{
152	// Test for empty ranges
153	if (__first1 == __last1 \|\| __first2 == __last2)
154	return __first1;
155
156	// Test for a pattern of length 1.
157	_ForwardIterator2 __p1(__first2);
158	if (++__p1 == __last2)
159	return std::__find_if(__first1, __last1,
160	__gnu_cxx::__ops::__iter_comp_iter(__predicate, __first2));
161
162	// General case.
163	_ForwardIterator1 __current = __first1;
164
165	for (;;)
166	{
167	__first1 =
168	std::__find_if(__first1, __last1,
169	__gnu_cxx::__ops::__iter_comp_iter(__predicate, __first2));
170
171	if (__first1 == __last1)
172	return __last1;
173
174	_ForwardIterator2 __p = __p1;
175	__current = __first1;
176	if (++__current == __last1)
177	return __last1;
178
179	while (__predicate(__current, __p))
180	{
181	if (++__p == __last2)
182	return __first1;
183	if (++__current == __last1)
184	return __last1;
185	}
186	++__first1;
187	}
188	return __first1;
189	}
190
191	// search_n
192
193	/**
194	* This is an helper function for search_n overloaded for forward iterators.
195	*/
196	template<typename _ForwardIterator, typename _Integer,
197	typename _UnaryPredicate>
198	_GLIBCXX20_CONSTEXPR
199	_ForwardIterator
200	__search_n_aux(_ForwardIterator __first, _ForwardIterator __last,
201	_Integer __count, _UnaryPredicate __unary_pred,
202	std::forward_iterator_tag)
203	{
204	__first = std::__find_if(__first, __last, __unary_pred);
205	while (__first != __last)
206	{
207	typename iterator_traits<_ForwardIterator>::difference_type
208	__n = __count;
209	_ForwardIterator __i = __first;
210	++__i;
211	while (__i != __last && __n != `1` && __unary_pred(__i))
212	{
213	++__i;
214	--__n;
215	}
216	if (__n == `1`)
217	return __first;
218	if (__i == __last)
219	return __last;
220	__first = std::__find_if(++__i, __last, __unary_pred);
221	}
222	return __last;
223	}
224
225	/**
226	* This is an helper function for search_n overloaded for random access
227	* iterators.
228	*/
229	template<typename _RandomAccessIter, typename _Integer,
230	typename _UnaryPredicate>
231	_GLIBCXX20_CONSTEXPR
232	_RandomAccessIter
233	__search_n_aux(_RandomAccessIter __first, _RandomAccessIter __last,
234	_Integer __count, _UnaryPredicate __unary_pred,
235	std::random_access_iterator_tag)
236	{
237	typedef typename std::iterator_traits<_RandomAccessIter>::difference_type
238	_DistanceType;
239
240	_DistanceType __tailSize = __last - __first;
241	_DistanceType __remainder = __count;
242
243	while (__remainder <= __tailSize) // the main loop...
244	{
245	__first += __remainder;
246	__tailSize -= __remainder;
247	// __first here is always pointing to one past the last element of
248	// next possible match.
249	_RandomAccessIter __backTrack = __first;
250	while (__unary_pred(--__backTrack))
251	{
252	if (--__remainder == `0`)
253	return (__first - __count); // Success
254	}
255	__remainder = __count + `1` - (__first - __backTrack);
256	}
257	return __last; // Failure
258	}
259
260	template<typename _ForwardIterator, typename _Integer,
261	typename _UnaryPredicate>
262	_GLIBCXX20_CONSTEXPR
263	_ForwardIterator
264	__search_n(_ForwardIterator __first, _ForwardIterator __last,
265	_Integer __count,
266	_UnaryPredicate __unary_pred)
267	{
268	if (__count <= `0`)
269	return __first;
270
271	if (__count == `1`)
272	return std::__find_if(__first, __last, __unary_pred);
273
274	return std::__search_n_aux(__first, __last, __count, __unary_pred,
275	std::__iterator_category(__first));
276	}
277
278	// find_end for forward iterators.
279	template<typename _ForwardIterator1, typename _ForwardIterator2,
280	typename _BinaryPredicate>
281	_GLIBCXX20_CONSTEXPR
282	_ForwardIterator1
283	__find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
284	_ForwardIterator2 __first2, _ForwardIterator2 __last2,
285	forward_iterator_tag, forward_iterator_tag,
286	_BinaryPredicate __comp)
287	{
288	if (__first2 == __last2)
289	return __last1;
290
291	_ForwardIterator1 __result = __last1;
292	while (`1`)
293	{
294	_ForwardIterator1 __new_result
295	= std::__search(__first1, __last1, __first2, __last2, __comp);
296	if (__new_result == __last1)
297	return __result;
298	else
299	{
300	__result = __new_result;
301	__first1 = __new_result;
302	++__first1;
303	}
304	}
305	}
306
307	// find_end for bidirectional iterators (much faster).
308	template<typename _BidirectionalIterator1, typename _BidirectionalIterator2,
309	typename _BinaryPredicate>
310	_GLIBCXX20_CONSTEXPR
311	_BidirectionalIterator1
312	__find_end(_BidirectionalIterator1 __first1,
313	_BidirectionalIterator1 __last1,
314	_BidirectionalIterator2 __first2,
315	_BidirectionalIterator2 __last2,
316	bidirectional_iterator_tag, bidirectional_iterator_tag,
317	_BinaryPredicate __comp)
318	{
319	// concept requirements
320	__glibcxx_function_requires(_BidirectionalIteratorConcept<
321	_BidirectionalIterator1>)
322	__glibcxx_function_requires(_BidirectionalIteratorConcept<
323	_BidirectionalIterator2>)
324
325	typedef reverse_iterator<_BidirectionalIterator1> _RevIterator1;
326	typedef reverse_iterator<_BidirectionalIterator2> _RevIterator2;
327
328	_RevIterator1 __rlast1(__first1);
329	_RevIterator2 __rlast2(__first2);
330	_RevIterator1 __rresult = std::__search(_RevIterator1(__last1), __rlast1,
331	_RevIterator2(__last2), __rlast2,
332	__comp);
333
334	if (__rresult == __rlast1)
335	return __last1;
336	else
337	{
338	_BidirectionalIterator1 __result = __rresult.base();
339	std::advance(__result, -std::distance(__first2, __last2));
340	return __result;
341	}
342	}
343
344	/**
345	* @brief Find last matching subsequence in a sequence.
346	* @ingroup non_mutating_algorithms
347	* @param __first1 Start of range to search.
348	* @param __last1 End of range to search.
349	* @param __first2 Start of sequence to match.
350	* @param __last2 End of sequence to match.
351	* @return The last iterator @c i in the range
352	* @p [__first1,__last1-(__last2-__first2)) such that @c *(i+N) ==
353	* @p *(__first2+N) for each @c N in the range @p
354	* [0,__last2-__first2), or @p __last1 if no such iterator exists.
355	*
356	* Searches the range @p [__first1,__last1) for a sub-sequence that
357	* compares equal value-by-value with the sequence given by @p
358	* [__first2,__last2) and returns an iterator to the __first
359	* element of the sub-sequence, or @p __last1 if the sub-sequence
360	* is not found. The sub-sequence will be the last such
361	* subsequence contained in [__first1,__last1).
362	*
363	* Because the sub-sequence must lie completely within the range @p
364	* [__first1,__last1) it must start at a position less than @p
365	* __last1-(__last2-__first2) where @p __last2-__first2 is the
366	* length of the sub-sequence. This means that the returned
367	* iterator @c i will be in the range @p
368	* [__first1,__last1-(__last2-__first2))
369	*/
370	template<typename _ForwardIterator1, typename _ForwardIterator2>
371	_GLIBCXX20_CONSTEXPR
372	inline _ForwardIterator1
373	find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
374	_ForwardIterator2 __first2, _ForwardIterator2 __last2)
375	{
376	// concept requirements
377	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator1>)
378	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator2>)
379	__glibcxx_function_requires(_EqualOpConcept<
380	typename iterator_traits<_ForwardIterator1>::value_type,
381	typename iterator_traits<_ForwardIterator2>::value_type>)
382	__glibcxx_requires_valid_range(__first1, __last1);
383	__glibcxx_requires_valid_range(__first2, __last2);
384
385	return std::__find_end(__first1, __last1, __first2, __last2,
386	std::__iterator_category(__first1),
387	std::__iterator_category(__first2),
388	__gnu_cxx::__ops::__iter_equal_to_iter());
389	}
390
391	/**
392	* @brief Find last matching subsequence in a sequence using a predicate.
393	* @ingroup non_mutating_algorithms
394	* @param __first1 Start of range to search.
395	* @param __last1 End of range to search.
396	* @param __first2 Start of sequence to match.
397	* @param __last2 End of sequence to match.
398	* @param __comp The predicate to use.
399	* @return The last iterator @c i in the range @p
400	* [__first1,__last1-(__last2-__first2)) such that @c
401	* predicate(*(i+N), @p (__first2+N)) is true for each @c N in the
402	* range @p [0,__last2-__first2), or @p __last1 if no such iterator
403	* exists.
404	*
405	* Searches the range @p [__first1,__last1) for a sub-sequence that
406	* compares equal value-by-value with the sequence given by @p
407	* [__first2,__last2) using comp as a predicate and returns an
408	* iterator to the first element of the sub-sequence, or @p __last1
409	* if the sub-sequence is not found. The sub-sequence will be the
410	* last such subsequence contained in [__first,__last1).
411	*
412	* Because the sub-sequence must lie completely within the range @p
413	* [__first1,__last1) it must start at a position less than @p
414	* __last1-(__last2-__first2) where @p __last2-__first2 is the
415	* length of the sub-sequence. This means that the returned
416	* iterator @c i will be in the range @p
417	* [__first1,__last1-(__last2-__first2))
418	*/
419	template<typename _ForwardIterator1, typename _ForwardIterator2,
420	typename _BinaryPredicate>
421	_GLIBCXX20_CONSTEXPR
422	inline _ForwardIterator1
423	find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
424	_ForwardIterator2 __first2, _ForwardIterator2 __last2,
425	_BinaryPredicate __comp)
426	{
427	// concept requirements
428	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator1>)
429	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator2>)
430	__glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
431	typename iterator_traits<_ForwardIterator1>::value_type,
432	typename iterator_traits<_ForwardIterator2>::value_type>)
433	__glibcxx_requires_valid_range(__first1, __last1);
434	__glibcxx_requires_valid_range(__first2, __last2);
435
436	return std::__find_end(__first1, __last1, __first2, __last2,
437	std::__iterator_category(__first1),
438	std::__iterator_category(__first2),
439	__gnu_cxx::__ops::__iter_comp_iter(__comp));
440	}
441
442	#if __cplusplus >= 201103L
443	/**
444	* @brief Checks that a predicate is true for all the elements
445	* of a sequence.
446	* @ingroup non_mutating_algorithms
447	* @param __first An input iterator.
448	* @param __last An input iterator.
449	* @param __pred A predicate.
450	* @return True if the check is true, false otherwise.
451	*
452	* Returns true if @p __pred is true for each element in the range
453	* @p [__first,__last), and false otherwise.
454	*/
455	template<typename _InputIterator, typename _Predicate>
456	_GLIBCXX20_CONSTEXPR
457	inline bool
458	all_of(_InputIterator __first, _InputIterator __last, _Predicate __pred)
459	{ return __last == std::find_if_not(__first, __last, __pred); }
460
461	/**
462	* @brief Checks that a predicate is false for all the elements
463	* of a sequence.
464	* @ingroup non_mutating_algorithms
465	* @param __first An input iterator.
466	* @param __last An input iterator.
467	* @param __pred A predicate.
468	* @return True if the check is true, false otherwise.
469	*
470	* Returns true if @p __pred is false for each element in the range
471	* @p [__first,__last), and false otherwise.
472	*/
473	template<typename _InputIterator, typename _Predicate>
474	_GLIBCXX20_CONSTEXPR
475	inline bool
476	none_of(_InputIterator __first, _InputIterator __last, _Predicate __pred)
477	{ return __last == _GLIBCXX_STD_A::find_if(__first, __last, __pred); }
478
479	/**
480	* @brief Checks that a predicate is true for at least one element
481	* of a sequence.
482	* @ingroup non_mutating_algorithms
483	* @param __first An input iterator.
484	* @param __last An input iterator.
485	* @param __pred A predicate.
486	* @return True if the check is true, false otherwise.
487	*
488	* Returns true if an element exists in the range @p
489	* [__first,__last) such that @p __pred is true, and false
490	* otherwise.
491	*/
492	template<typename _InputIterator, typename _Predicate>
493	_GLIBCXX20_CONSTEXPR
494	inline bool
495	any_of(_InputIterator __first, _InputIterator __last, _Predicate __pred)
496	{ return !std::none_of(__first, __last, __pred); }
497
498	/**
499	* @brief Find the first element in a sequence for which a
500	* predicate is false.
501	* @ingroup non_mutating_algorithms
502	* @param __first An input iterator.
503	* @param __last An input iterator.
504	* @param __pred A predicate.
505	* @return The first iterator @c i in the range @p [__first,__last)
506	* such that @p __pred(*i) is false, or @p __last if no such iterator exists.
507	*/
508	template<typename _InputIterator, typename _Predicate>
509	_GLIBCXX20_CONSTEXPR
510	inline _InputIterator
511	find_if_not(_InputIterator __first, _InputIterator __last,
512	_Predicate __pred)
513	{
514	// concept requirements
515	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
516	__glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
517	typename iterator_traits<_InputIterator>::value_type>)
518	__glibcxx_requires_valid_range(__first, __last);
519	return std::__find_if_not(__first, __last,
520	__gnu_cxx::__ops::__pred_iter(__pred));
521	}
522
523	/**
524	* @brief Checks whether the sequence is partitioned.
525	* @ingroup mutating_algorithms
526	* @param __first An input iterator.
527	* @param __last An input iterator.
528	* @param __pred A predicate.
529	* @return True if the range @p [__first,__last) is partioned by @p __pred,
530	* i.e. if all elements that satisfy @p __pred appear before those that
531	* do not.
532	*/
533	template<typename _InputIterator, typename _Predicate>
534	_GLIBCXX20_CONSTEXPR
535	inline bool
536	is_partitioned(_InputIterator __first, _InputIterator __last,
537	_Predicate __pred)
538	{
539	__first = std::find_if_not(__first, __last, __pred);
540	if (__first == __last)
541	return true;
542	++__first;
543	return std::none_of(__first, __last, __pred);
544	}
545
546	/**
547	* @brief Find the partition point of a partitioned range.
548	* @ingroup mutating_algorithms
549	* @param __first An iterator.
550	* @param __last Another iterator.
551	* @param __pred A predicate.
552	* @return An iterator @p mid such that @p all_of(__first, mid, __pred)
553	* and @p none_of(mid, __last, __pred) are both true.
554	*/
555	template<typename _ForwardIterator, typename _Predicate>
556	_GLIBCXX20_CONSTEXPR
557	_ForwardIterator
558	partition_point(_ForwardIterator __first, _ForwardIterator __last,
559	_Predicate __pred)
560	{
561	// concept requirements
562	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
563	__glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
564	typename iterator_traits<_ForwardIterator>::value_type>)
565
566	// A specific debug-mode test will be necessary...
567	__glibcxx_requires_valid_range(__first, __last);
568
569	typedef typename iterator_traits<_ForwardIterator>::difference_type
570	_DistanceType;
571
572	_DistanceType __len = std::distance(__first, __last);
573
574	while (__len > `0`)
575	{
576	_DistanceType __half = __len >> `1`;
577	_ForwardIterator __middle = __first;
578	std::advance(__middle, __half);
579	if (__pred(*__middle))
580	{
581	__first = __middle;
582	++__first;
583	__len = __len - __half - `1`;
584	}
585	else
586	__len = __half;
587	}
588	return __first;
589	}
590	#endif
591
592	template<typename _InputIterator, typename _OutputIterator,
593	typename _Predicate>
594	_GLIBCXX20_CONSTEXPR
595	_OutputIterator
596	__remove_copy_if(_InputIterator __first, _InputIterator __last,
597	_OutputIterator __result, _Predicate __pred)
598	{
599	for (; __first != __last; ++__first)
600	if (!__pred(__first))
601	{
602	__result = __first;
603	++__result;
604	}
605	return __result;
606	}
607
608	/**
609	* @brief Copy a sequence, removing elements of a given value.
610	* @ingroup mutating_algorithms
611	* @param __first An input iterator.
612	* @param __last An input iterator.
613	* @param __result An output iterator.
614	* @param __value The value to be removed.
615	* @return An iterator designating the end of the resulting sequence.
616	*
617	* Copies each element in the range @p [__first,__last) not equal
618	* to @p __value to the range beginning at @p __result.
619	* remove_copy() is stable, so the relative order of elements that
620	* are copied is unchanged.
621	*/
622	template<typename _InputIterator, typename _OutputIterator, typename _Tp>
623	_GLIBCXX20_CONSTEXPR
624	inline _OutputIterator
625	remove_copy(_InputIterator __first, _InputIterator __last,
626	_OutputIterator __result, const _Tp& __value)
627	{
628	// concept requirements
629	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
630	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
631	typename iterator_traits<_InputIterator>::value_type>)
632	__glibcxx_function_requires(_EqualOpConcept<
633	typename iterator_traits<_InputIterator>::value_type, _Tp>)
634	__glibcxx_requires_valid_range(__first, __last);
635
636	return std::__remove_copy_if(__first, __last, __result,
637	__gnu_cxx::__ops::__iter_equals_val(__value));
638	}
639
640	/**
641	* @brief Copy a sequence, removing elements for which a predicate is true.
642	* @ingroup mutating_algorithms
643	* @param __first An input iterator.
644	* @param __last An input iterator.
645	* @param __result An output iterator.
646	* @param __pred A predicate.
647	* @return An iterator designating the end of the resulting sequence.
648	*
649	* Copies each element in the range @p [__first,__last) for which
650	* @p __pred returns false to the range beginning at @p __result.
651	*
652	* remove_copy_if() is stable, so the relative order of elements that are
653	* copied is unchanged.
654	*/
655	template<typename _InputIterator, typename _OutputIterator,
656	typename _Predicate>
657	_GLIBCXX20_CONSTEXPR
658	inline _OutputIterator
659	remove_copy_if(_InputIterator __first, _InputIterator __last,
660	_OutputIterator __result, _Predicate __pred)
661	{
662	// concept requirements
663	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
664	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
665	typename iterator_traits<_InputIterator>::value_type>)
666	__glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
667	typename iterator_traits<_InputIterator>::value_type>)
668	__glibcxx_requires_valid_range(__first, __last);
669
670	return std::__remove_copy_if(__first, __last, __result,
671	__gnu_cxx::__ops::__pred_iter(__pred));
672	}
673
674	#if __cplusplus >= 201103L
675	/**
676	* @brief Copy the elements of a sequence for which a predicate is true.
677	* @ingroup mutating_algorithms
678	* @param __first An input iterator.
679	* @param __last An input iterator.
680	* @param __result An output iterator.
681	* @param __pred A predicate.
682	* @return An iterator designating the end of the resulting sequence.
683	*
684	* Copies each element in the range @p [__first,__last) for which
685	* @p __pred returns true to the range beginning at @p __result.
686	*
687	* copy_if() is stable, so the relative order of elements that are
688	* copied is unchanged.
689	*/
690	template<typename _InputIterator, typename _OutputIterator,
691	typename _Predicate>
692	_GLIBCXX20_CONSTEXPR
693	_OutputIterator
694	copy_if(_InputIterator __first, _InputIterator __last,
695	_OutputIterator __result, _Predicate __pred)
696	{
697	// concept requirements
698	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
699	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
700	typename iterator_traits<_InputIterator>::value_type>)
701	__glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
702	typename iterator_traits<_InputIterator>::value_type>)
703	__glibcxx_requires_valid_range(__first, __last);
704
705	for (; __first != __last; ++__first)
706	if (__pred(*__first))
707	{
708	__result = __first;
709	++__result;
710	}
711	return __result;
712	}
713
714	template<typename _InputIterator, typename _Size, typename _OutputIterator>
715	_GLIBCXX20_CONSTEXPR
716	_OutputIterator
717	__copy_n(_InputIterator __first, _Size __n,
718	_OutputIterator __result, input_iterator_tag)
719	{
720	return std::__niter_wrap(__result,
721	__copy_n_a(__first, __n,
722	std::__niter_base(__result), true));
723	}
724
725	template<typename _RandomAccessIterator, typename _Size,
726	typename _OutputIterator>
727	_GLIBCXX20_CONSTEXPR
728	inline _OutputIterator
729	__copy_n(_RandomAccessIterator __first, _Size __n,
730	_OutputIterator __result, random_access_iterator_tag)
731	{ return std::copy(__first, __first + __n, __result); }
732
733	/**
734	* @brief Copies the range [first,first+n) into [result,result+n).
735	* @ingroup mutating_algorithms
736	* @param __first An input iterator.
737	* @param __n The number of elements to copy.
738	* @param __result An output iterator.
739	* @return result+n.
740	*
741	* This inline function will boil down to a call to @c memmove whenever
742	* possible. Failing that, if random access iterators are passed, then the
743	* loop count will be known (and therefore a candidate for compiler
744	* optimizations such as unrolling).
745	*/
746	template<typename _InputIterator, typename _Size, typename _OutputIterator>
747	_GLIBCXX20_CONSTEXPR
748	inline _OutputIterator
749	copy_n(_InputIterator __first, _Size __n, _OutputIterator __result)
750	{
751	// concept requirements
752	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
753	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
754	typename iterator_traits<_InputIterator>::value_type>)
755
756	const auto __n2 = std::__size_to_integer(__n);
757	if (__n2 <= `0`)
758	return __result;
759
760	__glibcxx_requires_can_increment(__first, __n2);
761	__glibcxx_requires_can_increment(__result, __n2);
762
763	return std::__copy_n(__first, __n2, __result,
764	std::__iterator_category(__first));
765	}
766
767	/**
768	* @brief Copy the elements of a sequence to separate output sequences
769	* depending on the truth value of a predicate.
770	* @ingroup mutating_algorithms
771	* @param __first An input iterator.
772	* @param __last An input iterator.
773	* @param __out_true An output iterator.
774	* @param __out_false An output iterator.
775	* @param __pred A predicate.
776	* @return A pair designating the ends of the resulting sequences.
777	*
778	* Copies each element in the range @p [__first,__last) for which
779	* @p __pred returns true to the range beginning at @p out_true
780	* and each element for which @p __pred returns false to @p __out_false.
781	*/
782	template<typename _InputIterator, typename _OutputIterator1,
783	typename _OutputIterator2, typename _Predicate>
784	_GLIBCXX20_CONSTEXPR
785	pair<_OutputIterator1, _OutputIterator2>
786	partition_copy(_InputIterator __first, _InputIterator __last,
787	_OutputIterator1 __out_true, _OutputIterator2 __out_false,
788	_Predicate __pred)
789	{
790	// concept requirements
791	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
792	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator1,
793	typename iterator_traits<_InputIterator>::value_type>)
794	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator2,
795	typename iterator_traits<_InputIterator>::value_type>)
796	__glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
797	typename iterator_traits<_InputIterator>::value_type>)
798	__glibcxx_requires_valid_range(__first, __last);
799
800	for (; __first != __last; ++__first)
801	if (__pred(*__first))
802	{
803	__out_true = __first;
804	++__out_true;
805	}
806	else
807	{
808	__out_false = __first;
809	++__out_false;
810	}
811
812	return pair<_OutputIterator1, _OutputIterator2>(__out_true, __out_false);
813	}
814	#endif // C++11
815
816	/**
817	* @brief Remove elements from a sequence.
818	* @ingroup mutating_algorithms
819	* @param __first An input iterator.
820	* @param __last An input iterator.
821	* @param __value The value to be removed.
822	* @return An iterator designating the end of the resulting sequence.
823	*
824	* All elements equal to @p __value are removed from the range
825	* @p [__first,__last).
826	*
827	* remove() is stable, so the relative order of elements that are
828	* not removed is unchanged.
829	*
830	* Elements between the end of the resulting sequence and @p __last
831	* are still present, but their value is unspecified.
832	*/
833	template<typename _ForwardIterator, typename _Tp>
834	_GLIBCXX20_CONSTEXPR
835	inline _ForwardIterator
836	remove(_ForwardIterator __first, _ForwardIterator __last,
837	const _Tp& __value)
838	{
839	// concept requirements
840	__glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
841	_ForwardIterator>)
842	__glibcxx_function_requires(_EqualOpConcept<
843	typename iterator_traits<_ForwardIterator>::value_type, _Tp>)
844	__glibcxx_requires_valid_range(__first, __last);
845
846	return std::__remove_if(__first, __last,
847	__gnu_cxx::__ops::__iter_equals_val(__value));
848	}
849
850	/**
851	* @brief Remove elements from a sequence using a predicate.
852	* @ingroup mutating_algorithms
853	* @param __first A forward iterator.
854	* @param __last A forward iterator.
855	* @param __pred A predicate.
856	* @return An iterator designating the end of the resulting sequence.
857	*
858	* All elements for which @p __pred returns true are removed from the range
859	* @p [__first,__last).
860	*
861	* remove_if() is stable, so the relative order of elements that are
862	* not removed is unchanged.
863	*
864	* Elements between the end of the resulting sequence and @p __last
865	* are still present, but their value is unspecified.
866	*/
867	template<typename _ForwardIterator, typename _Predicate>
868	_GLIBCXX20_CONSTEXPR
869	inline _ForwardIterator
870	remove_if(_ForwardIterator __first, _ForwardIterator __last,
871	_Predicate __pred)
872	{
873	// concept requirements
874	__glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
875	_ForwardIterator>)
876	__glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
877	typename iterator_traits<_ForwardIterator>::value_type>)
878	__glibcxx_requires_valid_range(__first, __last);
879
880	return std::__remove_if(__first, __last,
881	__gnu_cxx::__ops::__pred_iter(__pred));
882	}
883
884	template<typename _ForwardIterator, typename _BinaryPredicate>
885	_GLIBCXX20_CONSTEXPR
886	_ForwardIterator
887	__adjacent_find(_ForwardIterator __first, _ForwardIterator __last,
888	_BinaryPredicate __binary_pred)
889	{
890	if (__first == __last)
891	return __last;
892	_ForwardIterator __next = __first;
893	while (++__next != __last)
894	{
895	if (__binary_pred(__first, __next))
896	return __first;
897	__first = __next;
898	}
899	return __last;
900	}
901
902	template<typename _ForwardIterator, typename _BinaryPredicate>
903	_GLIBCXX20_CONSTEXPR
904	_ForwardIterator
905	__unique(_ForwardIterator __first, _ForwardIterator __last,
906	_BinaryPredicate __binary_pred)
907	{
908	// Skip the beginning, if already unique.
909	__first = std::__adjacent_find(__first, __last, __binary_pred);
910	if (__first == __last)
911	return __last;
912
913	// Do the real copy work.
914	_ForwardIterator __dest = __first;
915	++__first;
916	while (++__first != __last)
917	if (!__binary_pred(__dest, __first))
918	++__dest = _GLIBCXX_MOVE(__first);
919	return ++__dest;
920	}
921
922	/**
923	* @brief Remove consecutive duplicate values from a sequence.
924	* @ingroup mutating_algorithms
925	* @param __first A forward iterator.
926	* @param __last A forward iterator.
927	* @return An iterator designating the end of the resulting sequence.
928	*
929	* Removes all but the first element from each group of consecutive
930	* values that compare equal.
931	* unique() is stable, so the relative order of elements that are
932	* not removed is unchanged.
933	* Elements between the end of the resulting sequence and @p __last
934	* are still present, but their value is unspecified.
935	*/
936	template<typename _ForwardIterator>
937	_GLIBCXX20_CONSTEXPR
938	inline _ForwardIterator
939	unique(_ForwardIterator __first, _ForwardIterator __last)
940	{
941	// concept requirements
942	__glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
943	_ForwardIterator>)
944	__glibcxx_function_requires(_EqualityComparableConcept<
945	typename iterator_traits<_ForwardIterator>::value_type>)
946	__glibcxx_requires_valid_range(__first, __last);
947
948	return std::__unique(__first, __last,
949	__gnu_cxx::__ops::__iter_equal_to_iter());
950	}
951
952	/**
953	* @brief Remove consecutive values from a sequence using a predicate.
954	* @ingroup mutating_algorithms
955	* @param __first A forward iterator.
956	* @param __last A forward iterator.
957	* @param __binary_pred A binary predicate.
958	* @return An iterator designating the end of the resulting sequence.
959	*
960	* Removes all but the first element from each group of consecutive
961	* values for which @p __binary_pred returns true.
962	* unique() is stable, so the relative order of elements that are
963	* not removed is unchanged.
964	* Elements between the end of the resulting sequence and @p __last
965	* are still present, but their value is unspecified.
966	*/
967	template<typename _ForwardIterator, typename _BinaryPredicate>
968	_GLIBCXX20_CONSTEXPR
969	inline _ForwardIterator
970	unique(_ForwardIterator __first, _ForwardIterator __last,
971	_BinaryPredicate __binary_pred)
972	{
973	// concept requirements
974	__glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
975	_ForwardIterator>)
976	__glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
977	typename iterator_traits<_ForwardIterator>::value_type,
978	typename iterator_traits<_ForwardIterator>::value_type>)
979	__glibcxx_requires_valid_range(__first, __last);
980
981	return std::__unique(__first, __last,
982	__gnu_cxx::__ops::__iter_comp_iter(__binary_pred));
983	}
984
985	/**
986	* This is an uglified
987	* unique_copy(_InputIterator, _InputIterator, _OutputIterator,
988	* _BinaryPredicate)
989	* overloaded for forward iterators and output iterator as result.
990	*/
991	template<typename _ForwardIterator, typename _OutputIterator,
992	typename _BinaryPredicate>
993	_GLIBCXX20_CONSTEXPR
994	_OutputIterator
995	__unique_copy(_ForwardIterator __first, _ForwardIterator __last,
996	_OutputIterator __result, _BinaryPredicate __binary_pred,
997	forward_iterator_tag, output_iterator_tag)
998	{
999	// concept requirements -- iterators already checked
1000	__glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
1001	typename iterator_traits<_ForwardIterator>::value_type,
1002	typename iterator_traits<_ForwardIterator>::value_type>)
1003
1004	_ForwardIterator __next = __first;
1005	__result = __first;
1006	while (++__next != __last)
1007	if (!__binary_pred(__first, __next))
1008	{
1009	__first = __next;
1010	++__result = __first;
1011	}
1012	return ++__result;
1013	}
1014
1015	/**
1016	* This is an uglified
1017	* unique_copy(_InputIterator, _InputIterator, _OutputIterator,
1018	* _BinaryPredicate)
1019	* overloaded for input iterators and output iterator as result.
1020	*/
1021	template<typename _InputIterator, typename _OutputIterator,
1022	typename _BinaryPredicate>
1023	_GLIBCXX20_CONSTEXPR
1024	_OutputIterator
1025	__unique_copy(_InputIterator __first, _InputIterator __last,
1026	_OutputIterator __result, _BinaryPredicate __binary_pred,
1027	input_iterator_tag, output_iterator_tag)
1028	{
1029	// concept requirements -- iterators already checked
1030	__glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
1031	typename iterator_traits<_InputIterator>::value_type,
1032	typename iterator_traits<_InputIterator>::value_type>)
1033
1034	typename iterator_traits<_InputIterator>::value_type __value = *__first;
1035	__decltype(__gnu_cxx::__ops::__iter_comp_val(__binary_pred))
1036	__rebound_pred
1037	= __gnu_cxx::__ops::__iter_comp_val(__binary_pred);
1038	*__result = __value;
1039	while (++__first != __last)
1040	if (!__rebound_pred(__first, __value))
1041	{
1042	__value = *__first;
1043	*++__result = __value;
1044	}
1045	return ++__result;
1046	}
1047
1048	/**
1049	* This is an uglified
1050	* unique_copy(_InputIterator, _InputIterator, _OutputIterator,
1051	* _BinaryPredicate)
1052	* overloaded for input iterators and forward iterator as result.
1053	*/
1054	template<typename _InputIterator, typename _ForwardIterator,
1055	typename _BinaryPredicate>
1056	_GLIBCXX20_CONSTEXPR
1057	_ForwardIterator
1058	__unique_copy(_InputIterator __first, _InputIterator __last,
1059	_ForwardIterator __result, _BinaryPredicate __binary_pred,
1060	input_iterator_tag, forward_iterator_tag)
1061	{
1062	// concept requirements -- iterators already checked
1063	__glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
1064	typename iterator_traits<_ForwardIterator>::value_type,
1065	typename iterator_traits<_InputIterator>::value_type>)
1066	__result = __first;
1067	while (++__first != __last)
1068	if (!__binary_pred(__result, __first))
1069	++__result = __first;
1070	return ++__result;
1071	}
1072
1073	/**
1074	* This is an uglified reverse(_BidirectionalIterator,
1075	* _BidirectionalIterator)
1076	* overloaded for bidirectional iterators.
1077	*/
1078	template<typename _BidirectionalIterator>
1079	_GLIBCXX20_CONSTEXPR
1080	void
1081	__reverse(_BidirectionalIterator __first, _BidirectionalIterator __last,
1082	bidirectional_iterator_tag)
1083	{
1084	while (true)
1085	if (__first == __last \|\| __first == --__last)
1086	return;
1087	else
1088	{
1089	std::iter_swap(__first, __last);
1090	++__first;
1091	}
1092	}
1093
1094	/**
1095	* This is an uglified reverse(_BidirectionalIterator,
1096	* _BidirectionalIterator)
1097	* overloaded for random access iterators.
1098	*/
1099	template<typename _RandomAccessIterator>
1100	_GLIBCXX20_CONSTEXPR
1101	void
1102	__reverse(_RandomAccessIterator __first, _RandomAccessIterator __last,
1103	random_access_iterator_tag)
1104	{
1105	if (__first == __last)
1106	return;
1107	--__last;
1108	while (__first < __last)
1109	{
1110	std::iter_swap(__first, __last);
1111	++__first;
1112	--__last;
1113	}
1114	}
1115
1116	/**
1117	* @brief Reverse a sequence.
1118	* @ingroup mutating_algorithms
1119	* @param __first A bidirectional iterator.
1120	* @param __last A bidirectional iterator.
1121	* @return reverse() returns no value.
1122	*
1123	* Reverses the order of the elements in the range @p [__first,__last),
1124	* so that the first element becomes the last etc.
1125	* For every @c i such that @p 0<=i<=(__last-__first)/2), @p reverse()
1126	* swaps @p (__first+i) and @p (__last-(i+1))
1127	*/
1128	template<typename _BidirectionalIterator>
1129	_GLIBCXX20_CONSTEXPR
1130	inline void
1131	reverse(_BidirectionalIterator __first, _BidirectionalIterator __last)
1132	{
1133	// concept requirements
1134	__glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<
1135	_BidirectionalIterator>)
1136	__glibcxx_requires_valid_range(__first, __last);
1137	std::__reverse(__first, __last, std::__iterator_category(__first));
1138	}
1139
1140	/**
1141	* @brief Copy a sequence, reversing its elements.
1142	* @ingroup mutating_algorithms
1143	* @param __first A bidirectional iterator.
1144	* @param __last A bidirectional iterator.
1145	* @param __result An output iterator.
1146	* @return An iterator designating the end of the resulting sequence.
1147	*
1148	* Copies the elements in the range @p [__first,__last) to the
1149	* range @p [__result,__result+(__last-__first)) such that the
1150	* order of the elements is reversed. For every @c i such that @p
1151	* 0<=i<=(__last-__first), @p reverse_copy() performs the
1152	* assignment @p (__result+(__last-__first)-1-i) = (__first+i).
1153	* The ranges @p [__first,__last) and @p
1154	* [__result,__result+(__last-__first)) must not overlap.
1155	*/
1156	template<typename _BidirectionalIterator, typename _OutputIterator>
1157	_GLIBCXX20_CONSTEXPR
1158	_OutputIterator
1159	reverse_copy(_BidirectionalIterator __first, _BidirectionalIterator __last,
1160	_OutputIterator __result)
1161	{
1162	// concept requirements
1163	__glibcxx_function_requires(_BidirectionalIteratorConcept<
1164	_BidirectionalIterator>)
1165	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
1166	typename iterator_traits<_BidirectionalIterator>::value_type>)
1167	__glibcxx_requires_valid_range(__first, __last);
1168
1169	while (__first != __last)
1170	{
1171	--__last;
1172	__result = __last;
1173	++__result;
1174	}
1175	return __result;
1176	}
1177
1178	/**
1179	* This is a helper function for the rotate algorithm specialized on RAIs.
1180	* It returns the greatest common divisor of two integer values.
1181	*/
1182	template<typename _EuclideanRingElement>
1183	_GLIBCXX20_CONSTEXPR
1184	_EuclideanRingElement
1185	__gcd(_EuclideanRingElement __m, _EuclideanRingElement __n)
1186	{
1187	while (__n != `0`)
1188	{
1189	_EuclideanRingElement __t = __m % __n;
1190	__m = __n;
1191	__n = __t;
1192	}
1193	return __m;
1194	}
1195
1196	_GLIBCXX_BEGIN_INLINE_ABI_NAMESPACE(_V2)
1197
1198	/// This is a helper function for the rotate algorithm.
1199	template<typename _ForwardIterator>
1200	_GLIBCXX20_CONSTEXPR
1201	_ForwardIterator
1202	__rotate(_ForwardIterator __first,
1203	_ForwardIterator __middle,
1204	_ForwardIterator __last,
1205	forward_iterator_tag)
1206	{
1207	if (__first == __middle)
1208	return __last;
1209	else if (__last == __middle)
1210	return __first;
1211
1212	_ForwardIterator __first2 = __middle;
1213	do
1214	{
1215	std::iter_swap(__first, __first2);
1216	++__first;
1217	++__first2;
1218	if (__first == __middle)
1219	__middle = __first2;
1220	}
1221	while (__first2 != __last);
1222
1223	_ForwardIterator __ret = __first;
1224
1225	__first2 = __middle;
1226
1227	while (__first2 != __last)
1228	{
1229	std::iter_swap(__first, __first2);
1230	++__first;
1231	++__first2;
1232	if (__first == __middle)
1233	__middle = __first2;
1234	else if (__first2 == __last)
1235	__first2 = __middle;
1236	}
1237	return __ret;
1238	}
1239
1240	/// This is a helper function for the rotate algorithm.
1241	template<typename _BidirectionalIterator>
1242	_GLIBCXX20_CONSTEXPR
1243	_BidirectionalIterator
1244	__rotate(_BidirectionalIterator __first,
1245	_BidirectionalIterator __middle,
1246	_BidirectionalIterator __last,
1247	bidirectional_iterator_tag)
1248	{
1249	// concept requirements
1250	__glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<
1251	_BidirectionalIterator>)
1252
1253	if (__first == __middle)
1254	return __last;
1255	else if (__last == __middle)
1256	return __first;
1257
1258	std::__reverse(__first, __middle, bidirectional_iterator_tag ());
1259	std::__reverse(__middle, __last, bidirectional_iterator_tag ());
1260
1261	while (__first != __middle && __middle != __last)
1262	{
1263	std::iter_swap(__first, --__last);
1264	++__first;
1265	}
1266
1267	if (__first == __middle)
1268	{
1269	std::__reverse(__middle, __last, bidirectional_iterator_tag ());
1270	return __last;
1271	}
1272	else
1273	{
1274	std::__reverse(__first, __middle, bidirectional_iterator_tag ());
1275	return __first;
1276	}
1277	}
1278
1279	/// This is a helper function for the rotate algorithm.
1280	template<typename _RandomAccessIterator>
1281	_GLIBCXX20_CONSTEXPR
1282	_RandomAccessIterator
1283	__rotate(_RandomAccessIterator __first,
1284	_RandomAccessIterator __middle,
1285	_RandomAccessIterator __last,
1286	random_access_iterator_tag)
1287	{
1288	// concept requirements
1289	__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
1290	_RandomAccessIterator>)
1291
1292	if (__first == __middle)
1293	return __last;
1294	else if (__last == __middle)
1295	return __first;
1296
1297	typedef typename iterator_traits<_RandomAccessIterator>::difference_type
1298	_Distance;
1299	typedef typename iterator_traits<_RandomAccessIterator>::value_type
1300	_ValueType;
1301
1302	_Distance __n = __last - __first;
1303	_Distance __k = __middle - __first;
1304
1305	if (__k == __n - __k)
1306	{
1307	std::swap_ranges(__first, __middle, __middle);
1308	return __middle;
1309	}
1310
1311	_RandomAccessIterator __p = __first;
1312	_RandomAccessIterator __ret = __first + (__last - __middle);
1313
1314	for (;;)
1315	{
1316	if (__k < __n - __k)
1317	{
1318	if (__is_pod(_ValueType) && __k == `1`)
1319	{
1320	_ValueType __t = _GLIBCXX_MOVE(*__p);
1321	_GLIBCXX_MOVE3(__p + `1`, __p + __n, __p);
1322	*(__p + __n - `1`) = _GLIBCXX_MOVE(__t);
1323	return __ret;
1324	}
1325	_RandomAccessIterator __q = __p + __k;
1326	for (_Distance __i = `0`; __i < __n - __k; ++ __i)
1327	{
1328	std::iter_swap(__p, __q);
1329	++__p;
1330	++__q;
1331	}
1332	__n %= __k;
1333	if (__n == `0`)
1334	return __ret;
1335	std::swap(__n, __k);
1336	__k = __n - __k;
1337	}
1338	else
1339	{
1340	__k = __n - __k;
1341	if (__is_pod(_ValueType) && __k == `1`)
1342	{
1343	_ValueType __t = _GLIBCXX_MOVE(*(__p + __n - `1`));
1344	_GLIBCXX_MOVE_BACKWARD3(__p, __p + __n - `1`, __p + __n);
1345	*__p = _GLIBCXX_MOVE(__t);
1346	return __ret;
1347	}
1348	_RandomAccessIterator __q = __p + __n;
1349	__p = __q - __k;
1350	for (_Distance __i = `0`; __i < __n - __k; ++ __i)
1351	{
1352	--__p;
1353	--__q;
1354	std::iter_swap(__p, __q);
1355	}
1356	__n %= __k;
1357	if (__n == `0`)
1358	return __ret;
1359	std::swap(__n, __k);
1360	}
1361	}
1362	}
1363
1364	// _GLIBCXX_RESOLVE_LIB_DEFECTS
1365	// DR 488. rotate throws away useful information
1366	/**
1367	* @brief Rotate the elements of a sequence.
1368	* @ingroup mutating_algorithms
1369	* @param __first A forward iterator.
1370	* @param __middle A forward iterator.
1371	* @param __last A forward iterator.
1372	* @return first + (last - middle).
1373	*
1374	* Rotates the elements of the range @p [__first,__last) by
1375	* @p (__middle - __first) positions so that the element at @p __middle
1376	* is moved to @p __first, the element at @p __middle+1 is moved to
1377	* @p __first+1 and so on for each element in the range
1378	* @p [__first,__last).
1379	*
1380	* This effectively swaps the ranges @p [__first,__middle) and
1381	* @p [__middle,__last).
1382	*
1383	* Performs
1384	* @p (__first+(n+(__last-__middle))%(__last-__first))=(__first+n)
1385	* for each @p n in the range @p [0,__last-__first).
1386	*/
1387	template<typename _ForwardIterator>
1388	_GLIBCXX20_CONSTEXPR
1389	inline _ForwardIterator
1390	rotate(_ForwardIterator __first, _ForwardIterator __middle,
1391	_ForwardIterator __last)
1392	{
1393	// concept requirements
1394	__glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
1395	_ForwardIterator>)
1396	__glibcxx_requires_valid_range(__first, __middle);
1397	__glibcxx_requires_valid_range(__middle, __last);
1398
1399	return std::__rotate(__first, __middle, __last,
1400	std::__iterator_category(__first));
1401	}
1402
1403	_GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
1404
1405	/**
1406	* @brief Copy a sequence, rotating its elements.
1407	* @ingroup mutating_algorithms
1408	* @param __first A forward iterator.
1409	* @param __middle A forward iterator.
1410	* @param __last A forward iterator.
1411	* @param __result An output iterator.
1412	* @return An iterator designating the end of the resulting sequence.
1413	*
1414	* Copies the elements of the range @p [__first,__last) to the
1415	* range beginning at @result, rotating the copied elements by
1416	* @p (__middle-__first) positions so that the element at @p __middle
1417	* is moved to @p __result, the element at @p __middle+1 is moved
1418	* to @p __result+1 and so on for each element in the range @p
1419	* [__first,__last).
1420	*
1421	* Performs
1422	* @p (__result+(n+(__last-__middle))%(__last-__first))=(__first+n)
1423	* for each @p n in the range @p [0,__last-__first).
1424	*/
1425	template<typename _ForwardIterator, typename _OutputIterator>
1426	_GLIBCXX20_CONSTEXPR
1427	inline _OutputIterator
1428	rotate_copy(_ForwardIterator __first, _ForwardIterator __middle,
1429	_ForwardIterator __last, _OutputIterator __result)
1430	{
1431	// concept requirements
1432	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
1433	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
1434	typename iterator_traits<_ForwardIterator>::value_type>)
1435	__glibcxx_requires_valid_range(__first, __middle);
1436	__glibcxx_requires_valid_range(__middle, __last);
1437
1438	return std::copy(__first, __middle,
1439	std::copy(__middle, __last, __result));
1440	}
1441
1442	/// This is a helper function...
1443	template<typename _ForwardIterator, typename _Predicate>
1444	_GLIBCXX20_CONSTEXPR
1445	_ForwardIterator
1446	__partition(_ForwardIterator __first, _ForwardIterator __last,
1447	_Predicate __pred, forward_iterator_tag)
1448	{
1449	if (__first == __last)
1450	return __first;
1451
1452	while (__pred(*__first))
1453	if (++__first == __last)
1454	return __first;
1455
1456	_ForwardIterator __next = __first;
1457
1458	while (++__next != __last)
1459	if (__pred(*__next))
1460	{
1461	std::iter_swap(__first, __next);
1462	++__first;
1463	}
1464
1465	return __first;
1466	}
1467
1468	/// This is a helper function...
1469	template<typename _BidirectionalIterator, typename _Predicate>
1470	_GLIBCXX20_CONSTEXPR
1471	_BidirectionalIterator
1472	__partition(_BidirectionalIterator __first, _BidirectionalIterator __last,
1473	_Predicate __pred, bidirectional_iterator_tag)
1474	{
1475	while (true)
1476	{
1477	while (true)
1478	if (__first == __last)
1479	return __first;
1480	else if (__pred(*__first))
1481	++__first;
1482	else
1483	break;
1484	--__last;
1485	while (true)
1486	if (__first == __last)
1487	return __first;
1488	else if (!bool(__pred(*__last)))
1489	--__last;
1490	else
1491	break;
1492	std::iter_swap(__first, __last);
1493	++__first;
1494	}
1495	}
1496
1497	#if _GLIBCXX_HOSTED
1498	// partition
1499
1500	/// This is a helper function...
1501	/// Requires __first != __last and !__pred(__first)
1502	/// and __len == distance(__first, __last).
1503	///
1504	/// !__pred(__first) allows us to guarantee that we don't
1505	/// move-assign an element onto itself.
1506	template<typename _ForwardIterator, typename _Pointer, typename _Predicate,
1507	typename _Distance>
1508	_ForwardIterator
1509	__stable_partition_adaptive(_ForwardIterator __first,
1510	_ForwardIterator __last,
1511	_Predicate __pred, _Distance __len,
1512	_Pointer __buffer,
1513	_Distance __buffer_size)
1514	{
1515	if (__len == `1`)
1516	return __first;
1517
1518	if (__len <= __buffer_size)
1519	{
1520	_ForwardIterator __result1 = __first;
1521	_Pointer __result2 = __buffer;
1522
1523	// The precondition guarantees that !__pred(__first), so
1524	// move that element to the buffer before starting the loop.
1525	// This ensures that we only call __pred once per element.
1526	__result2 = _GLIBCXX_MOVE(__first);
1527	++__result2;
1528	++__first;
1529	for (; __first != __last; ++__first)
1530	if (__pred(__first))
1531	{
1532	__result1 = _GLIBCXX_MOVE(__first);
1533	++__result1;
1534	}
1535	else
1536	{
1537	__result2 = _GLIBCXX_MOVE(__first);
1538	++__result2;
1539	}
1540
1541	_GLIBCXX_MOVE3(__buffer, __result2, __result1);
1542	return __result1;
1543	}
1544
1545	_ForwardIterator __middle = __first;
1546	std::advance(__middle, __len / `2`);
1547	_ForwardIterator __left_split =
1548	std::__stable_partition_adaptive(__first, __middle, __pred,
1549	__len / `2`, __buffer,
1550	__buffer_size);
1551
1552	// Advance past true-predicate values to satisfy this
1553	// function's preconditions.
1554	_Distance __right_len = __len - __len / `2`;
1555	_ForwardIterator __right_split =
1556	std::__find_if_not_n(__middle, __right_len, __pred);
1557
1558	if (__right_len)
1559	__right_split =
1560	std::__stable_partition_adaptive(__right_split, __last, __pred,
1561	__right_len,
1562	__buffer, __buffer_size);
1563
1564	return std::rotate(__left_split, __middle, __right_split);
1565	}
1566
1567	template<typename _ForwardIterator, typename _Predicate>
1568	_ForwardIterator
1569	__stable_partition(_ForwardIterator __first, _ForwardIterator __last,
1570	_Predicate __pred)
1571	{
1572	__first = std::__find_if_not(__first, __last, __pred);
1573
1574	if (__first == __last)
1575	return __first;
1576
1577	typedef typename iterator_traits<_ForwardIterator>::value_type
1578	_ValueType;
1579	typedef typename iterator_traits<_ForwardIterator>::difference_type
1580	_DistanceType;
1581
1582	_Temporary_buffer<_ForwardIterator, _ValueType>
1583	__buf(__first, std::distance(__first, __last));
1584	return
1585	std::__stable_partition_adaptive(__first, __last, __pred,
1586	_DistanceType(__buf.requested_size()),
1587	__buf.begin(),
1588	_DistanceType(__buf.size()));
1589	}
1590
1591	/**
1592	* @brief Move elements for which a predicate is true to the beginning
1593	* of a sequence, preserving relative ordering.
1594	* @ingroup mutating_algorithms
1595	* @param __first A forward iterator.
1596	* @param __last A forward iterator.
1597	* @param __pred A predicate functor.
1598	* @return An iterator @p middle such that @p __pred(i) is true for each
1599	* iterator @p i in the range @p [first,middle) and false for each @p i
1600	* in the range @p [middle,last).
1601	*
1602	* Performs the same function as @p partition() with the additional
1603	* guarantee that the relative ordering of elements in each group is
1604	* preserved, so any two elements @p x and @p y in the range
1605	* @p [__first,__last) such that @p __pred(x)==__pred(y) will have the same
1606	* relative ordering after calling @p stable_partition().
1607	*/
1608	template<typename _ForwardIterator, typename _Predicate>
1609	inline _ForwardIterator
1610	stable_partition(_ForwardIterator __first, _ForwardIterator __last,
1611	_Predicate __pred)
1612	{
1613	// concept requirements
1614	__glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
1615	_ForwardIterator>)
1616	__glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
1617	typename iterator_traits<_ForwardIterator>::value_type>)
1618	__glibcxx_requires_valid_range(__first, __last);
1619
1620	return std::__stable_partition(__first, __last,
1621	__gnu_cxx::__ops::__pred_iter(__pred));
1622	}
1623	#endif // HOSTED
1624
1625	/// @cond undocumented
1626
1627	/// This is a helper function for the sort routines.
1628	template<typename _RandomAccessIterator, typename _Compare>
1629	_GLIBCXX20_CONSTEXPR
1630	void
1631	__heap_select(_RandomAccessIterator __first,
1632	_RandomAccessIterator __middle,
1633	_RandomAccessIterator __last, _Compare __comp)
1634	{
1635	std::__make_heap(__first, __middle, __comp);
1636	for (_RandomAccessIterator __i = __middle; __i < __last; ++__i)
1637	if (__comp(__i, __first))
1638	std::__pop_heap(__first, __middle, __i, __comp);
1639	}
1640
1641	// partial_sort
1642
1643	template<typename _InputIterator, typename _RandomAccessIterator,
1644	typename _Compare>
1645	_GLIBCXX20_CONSTEXPR
1646	_RandomAccessIterator
1647	__partial_sort_copy(_InputIterator __first, _InputIterator __last,
1648	_RandomAccessIterator __result_first,
1649	_RandomAccessIterator __result_last,
1650	_Compare __comp)
1651	{
1652	typedef typename iterator_traits<_InputIterator>::value_type
1653	_InputValueType;
1654	typedef iterator_traits<_RandomAccessIterator> _RItTraits;
1655	typedef typename _RItTraits::difference_type _DistanceType;
1656
1657	if (__result_first == __result_last)
1658	return __result_last;
1659	_RandomAccessIterator __result_real_last = __result_first;
1660	while (__first != __last && __result_real_last != __result_last)
1661	{
1662	__result_real_last = __first;
1663	++__result_real_last;
1664	++__first;
1665	}
1666
1667	std::__make_heap(__result_first, __result_real_last, __comp);
1668	while (__first != __last)
1669	{
1670	if (__comp(__first, __result_first))
1671	std::__adjust_heap(__result_first, _DistanceType(`0`),
1672	_DistanceType(__result_real_last
1673	- __result_first),
1674	_InputValueType(*__first), __comp);
1675	++__first;
1676	}
1677	std::__sort_heap(__result_first, __result_real_last, __comp);
1678	return __result_real_last;
1679	}
1680
1681	/// @endcond
1682
1683	/**
1684	* @brief Copy the smallest elements of a sequence.
1685	* @ingroup sorting_algorithms
1686	* @param __first An iterator.
1687	* @param __last Another iterator.
1688	* @param __result_first A random-access iterator.
1689	* @param __result_last Another random-access iterator.
1690	* @return An iterator indicating the end of the resulting sequence.
1691	*
1692	* Copies and sorts the smallest `N` values from the range
1693	* `[__first, __last)` to the range beginning at `__result_first`, where
1694	* the number of elements to be copied, `N`, is the smaller of
1695	* `(__last - __first)` and `(__result_last - __result_first)`.
1696	* After the sort if `i` and `j` are iterators in the range
1697	* `[__result_first,__result_first + N)` such that `i` precedes `j` then
1698	* `j < i` is false.
1699	* The value returned is `__result_first + N`.
1700	*/
1701	template<typename _InputIterator, typename _RandomAccessIterator>
1702	_GLIBCXX20_CONSTEXPR
1703	inline _RandomAccessIterator
1704	partial_sort_copy(_InputIterator __first, _InputIterator __last,
1705	_RandomAccessIterator __result_first,
1706	_RandomAccessIterator __result_last)
1707	{
1708	#ifdef _GLIBCXX_CONCEPT_CHECKS
1709	typedef typename iterator_traits<_InputIterator>::value_type
1710	_InputValueType;
1711	typedef typename iterator_traits<_RandomAccessIterator>::value_type
1712	_OutputValueType;
1713	#endif
1714
1715	// concept requirements
1716	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
1717	__glibcxx_function_requires(_ConvertibleConcept<_InputValueType,
1718	_OutputValueType>)
1719	__glibcxx_function_requires(_LessThanOpConcept<_InputValueType,
1720	_OutputValueType>)
1721	__glibcxx_function_requires(_LessThanComparableConcept<_OutputValueType>)
1722	__glibcxx_requires_valid_range(__first, __last);
1723	__glibcxx_requires_irreflexive(__first, __last);
1724	__glibcxx_requires_valid_range(__result_first, __result_last);
1725
1726	return std::__partial_sort_copy(__first, __last,
1727	__result_first, __result_last,
1728	__gnu_cxx::__ops::__iter_less_iter());
1729	}
1730
1731	/**
1732	* @brief Copy the smallest elements of a sequence using a predicate for
1733	* comparison.
1734	* @ingroup sorting_algorithms
1735	* @param __first An input iterator.
1736	* @param __last Another input iterator.
1737	* @param __result_first A random-access iterator.
1738	* @param __result_last Another random-access iterator.
1739	* @param __comp A comparison functor.
1740	* @return An iterator indicating the end of the resulting sequence.
1741	*
1742	* Copies and sorts the smallest `N` values from the range
1743	* `[__first, __last)` to the range beginning at `result_first`, where
1744	* the number of elements to be copied, `N`, is the smaller of
1745	* `(__last - __first)` and `(__result_last - __result_first)`.
1746	* After the sort if `i` and `j` are iterators in the range
1747	* `[__result_first, __result_first + N)` such that `i` precedes `j` then
1748	* `__comp(j, i)` is false.
1749	* The value returned is `__result_first + N`.
1750	*/
1751	template<typename _InputIterator, typename _RandomAccessIterator,
1752	typename _Compare>
1753	_GLIBCXX20_CONSTEXPR
1754	inline _RandomAccessIterator
1755	partial_sort_copy(_InputIterator __first, _InputIterator __last,
1756	_RandomAccessIterator __result_first,
1757	_RandomAccessIterator __result_last,
1758	_Compare __comp)
1759	{
1760	#ifdef _GLIBCXX_CONCEPT_CHECKS
1761	typedef typename iterator_traits<_InputIterator>::value_type
1762	_InputValueType;
1763	typedef typename iterator_traits<_RandomAccessIterator>::value_type
1764	_OutputValueType;
1765	#endif
1766
1767	// concept requirements
1768	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
1769	__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
1770	_RandomAccessIterator>)
1771	__glibcxx_function_requires(_ConvertibleConcept<_InputValueType,
1772	_OutputValueType>)
1773	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
1774	_InputValueType, _OutputValueType>)
1775	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
1776	_OutputValueType, _OutputValueType>)
1777	__glibcxx_requires_valid_range(__first, __last);
1778	__glibcxx_requires_irreflexive_pred(__first, __last, __comp);
1779	__glibcxx_requires_valid_range(__result_first, __result_last);
1780
1781	return std::__partial_sort_copy(__first, __last,
1782	__result_first, __result_last,
1783	__gnu_cxx::__ops::__iter_comp_iter(__comp));
1784	}
1785
1786	/// @cond undocumented
1787
1788	/// This is a helper function for the sort routine.
1789	template<typename _RandomAccessIterator, typename _Compare>
1790	_GLIBCXX20_CONSTEXPR
1791	void
1792	__unguarded_linear_insert(_RandomAccessIterator __last,
1793	_Compare __comp)
1794	{
1795	typename iterator_traits<_RandomAccessIterator>::value_type
1796	__val = _GLIBCXX_MOVE(*__last);
1797	_RandomAccessIterator __next = __last;
1798	--__next;
1799	while (__comp(__val, __next))
1800	{
1801	__last = _GLIBCXX_MOVE(__next);
1802	__last = __next;
1803	--__next;
1804	}
1805	*__last = _GLIBCXX_MOVE(__val);
1806	}
1807
1808	/// This is a helper function for the sort routine.
1809	template<typename _RandomAccessIterator, typename _Compare>
1810	_GLIBCXX20_CONSTEXPR
1811	void
1812	__insertion_sort(_RandomAccessIterator __first,
1813	_RandomAccessIterator __last, _Compare __comp)
1814	{
1815	if (__first == __last) return;
1816
1817	for (_RandomAccessIterator __i = __first + `1`; __i != __last; ++__i)
1818	{
1819	if (__comp(__i, __first))
1820	{
1821	typename iterator_traits<_RandomAccessIterator>::value_type
1822	__val = _GLIBCXX_MOVE(*__i);
1823	_GLIBCXX_MOVE_BACKWARD3(__first, __i, __i + `1`);
1824	*__first = _GLIBCXX_MOVE(__val);
1825	}
1826	else
1827	std::__unguarded_linear_insert(__i,
1828	__gnu_cxx::__ops::__val_comp_iter(__comp));
1829	}
1830	}
1831
1832	/// This is a helper function for the sort routine.
1833	template<typename _RandomAccessIterator, typename _Compare>
1834	_GLIBCXX20_CONSTEXPR
1835	inline void
1836	__unguarded_insertion_sort(_RandomAccessIterator __first,
1837	_RandomAccessIterator __last, _Compare __comp)
1838	{
1839	for (_RandomAccessIterator __i = __first; __i != __last; ++__i)
1840	std::__unguarded_linear_insert(__i,
1841	__gnu_cxx::__ops::__val_comp_iter(__comp));
1842	}
1843
1844	/**
1845	* @doctodo
1846	* This controls some aspect of the sort routines.
1847	*/
1848	enum { _S_threshold = `16` };
1849
1850	/// This is a helper function for the sort routine.
1851	template<typename _RandomAccessIterator, typename _Compare>
1852	_GLIBCXX20_CONSTEXPR
1853	void
1854	__final_insertion_sort(_RandomAccessIterator __first,
1855	_RandomAccessIterator __last, _Compare __comp)
1856	{
1857	if (__last - __first > int(_S_threshold))
1858	{
1859	std::__insertion_sort(__first, __first + int(_S_threshold), __comp);
1860	std::__unguarded_insertion_sort(__first + int(_S_threshold), __last,
1861	__comp);
1862	}
1863	else
1864	std::__insertion_sort(__first, __last, __comp);
1865	}
1866
1867	/// This is a helper function...
1868	template<typename _RandomAccessIterator, typename _Compare>
1869	_GLIBCXX20_CONSTEXPR
1870	_RandomAccessIterator
1871	__unguarded_partition(_RandomAccessIterator __first,
1872	_RandomAccessIterator __last,
1873	_RandomAccessIterator __pivot, _Compare __comp)
1874	{
1875	while (true)
1876	{
1877	while (__comp(__first, __pivot))
1878	++__first;
1879	--__last;
1880	while (__comp(__pivot, __last))
1881	--__last;
1882	if (!(__first < __last))
1883	return __first;
1884	std::iter_swap(__first, __last);
1885	++__first;
1886	}
1887	}
1888
1889	/// This is a helper function...
1890	template<typename _RandomAccessIterator, typename _Compare>
1891	_GLIBCXX20_CONSTEXPR
1892	inline _RandomAccessIterator
1893	__unguarded_partition_pivot(_RandomAccessIterator __first,
1894	_RandomAccessIterator __last, _Compare __comp)
1895	{
1896	_RandomAccessIterator __mid = __first + (__last - __first) / `2`;
1897	std::__move_median_to_first(__first, __first + `1`, __mid, __last - `1`,
1898	__comp);
1899	return std::__unguarded_partition(__first + `1`, __last, __first, __comp);
1900	}
1901
1902	template<typename _RandomAccessIterator, typename _Compare>
1903	_GLIBCXX20_CONSTEXPR
1904	inline void
1905	__partial_sort(_RandomAccessIterator __first,
1906	_RandomAccessIterator __middle,
1907	_RandomAccessIterator __last,
1908	_Compare __comp)
1909	{
1910	std::__heap_select(__first, __middle, __last, __comp);
1911	std::__sort_heap(__first, __middle, __comp);
1912	}
1913
1914	/// This is a helper function for the sort routine.
1915	template<typename _RandomAccessIterator, typename _Size, typename _Compare>
1916	_GLIBCXX20_CONSTEXPR
1917	void
1918	__introsort_loop(_RandomAccessIterator __first,
1919	_RandomAccessIterator __last,
1920	_Size __depth_limit, _Compare __comp)
1921	{
1922	while (__last - __first > int(_S_threshold))
1923	{
1924	if (__depth_limit == `0`)
1925	{
1926	std::__partial_sort(__first, __last, __last, __comp);
1927	return;
1928	}
1929	--__depth_limit;
1930	_RandomAccessIterator __cut =
1931	std::__unguarded_partition_pivot(__first, __last, __comp);
1932	std::__introsort_loop(__cut, __last, __depth_limit, __comp);
1933	__last = __cut;
1934	}
1935	}
1936
1937	// sort
1938
1939	template<typename _RandomAccessIterator, typename _Compare>
1940	_GLIBCXX20_CONSTEXPR
1941	inline void
1942	__sort(_RandomAccessIterator __first, _RandomAccessIterator __last,
1943	_Compare __comp)
1944	{
1945	if (__first != __last)
1946	{
1947	std::__introsort_loop(__first, __last,
1948	std::__lg(__last - __first) * `2`,
1949	__comp);
1950	std::__final_insertion_sort(__first, __last, __comp);
1951	}
1952	}
1953
1954	template<typename _RandomAccessIterator, typename _Size, typename _Compare>
1955	_GLIBCXX20_CONSTEXPR
1956	void
1957	__introselect(_RandomAccessIterator __first, _RandomAccessIterator __nth,
1958	_RandomAccessIterator __last, _Size __depth_limit,
1959	_Compare __comp)
1960	{
1961	while (__last - __first > `3`)
1962	{
1963	if (__depth_limit == `0`)
1964	{
1965	std::__heap_select(__first, __nth + `1`, __last, __comp);
1966	// Place the nth largest element in its final position.
1967	std::iter_swap(__first, __nth);
1968	return;
1969	}
1970	--__depth_limit;
1971	_RandomAccessIterator __cut =
1972	std::__unguarded_partition_pivot(__first, __last, __comp);
1973	if (__cut <= __nth)
1974	__first = __cut;
1975	else
1976	__last = __cut;
1977	}
1978	std::__insertion_sort(__first, __last, __comp);
1979	}
1980
1981	/// @endcond
1982
1983	// nth_element
1984
1985	// lower_bound moved to stl_algobase.h
1986
1987	/**
1988	* @brief Finds the first position in which `__val` could be inserted
1989	* without changing the ordering.
1990	* @ingroup binary_search_algorithms
1991	* @param __first An iterator to the start of a sorted range.
1992	* @param __last A past-the-end iterator for the sorted range.
1993	* @param __val The search term.
1994	* @param __comp A functor to use for comparisons.
1995	* @return An iterator pointing to the first element _not less than_
1996	* `__val`, or `end()` if every element is less than `__val`.
1997	* @ingroup binary_search_algorithms
1998	*
1999	* The comparison function should have the same effects on ordering as
2000	* the function used for the initial sort.
2001	*/
2002	template<typename _ForwardIterator, typename _Tp, typename _Compare>
2003	_GLIBCXX20_CONSTEXPR
2004	inline _ForwardIterator
2005	lower_bound(_ForwardIterator __first, _ForwardIterator __last,
2006	const _Tp& __val, _Compare __comp)
2007	{
2008	// concept requirements
2009	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
2010	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
2011	typename iterator_traits<_ForwardIterator>::value_type, _Tp>)
2012	__glibcxx_requires_partitioned_lower_pred(__first, __last,
2013	__val, __comp);
2014
2015	return std::__lower_bound(__first, __last, __val,
2016	__gnu_cxx::__ops::__iter_comp_val(__comp));
2017	}
2018
2019	template<typename _ForwardIterator, typename _Tp, typename _Compare>
2020	_GLIBCXX20_CONSTEXPR
2021	_ForwardIterator
2022	__upper_bound(_ForwardIterator __first, _ForwardIterator __last,
2023	const _Tp& __val, _Compare __comp)
2024	{
2025	typedef typename iterator_traits<_ForwardIterator>::difference_type
2026	_DistanceType;
2027
2028	_DistanceType __len = std::distance(__first, __last);
2029
2030	while (__len > `0`)
2031	{
2032	_DistanceType __half = __len >> `1`;
2033	_ForwardIterator __middle = __first;
2034	std::advance(__middle, __half);
2035	if (__comp(__val, __middle))
2036	__len = __half;
2037	else
2038	{
2039	__first = __middle;
2040	++__first;
2041	__len = __len - __half - `1`;
2042	}
2043	}
2044	return __first;
2045	}
2046
2047	/**
2048	* @brief Finds the last position in which @p __val could be inserted
2049	* without changing the ordering.
2050	* @ingroup binary_search_algorithms
2051	* @param __first An iterator.
2052	* @param __last Another iterator.
2053	* @param __val The search term.
2054	* @return An iterator pointing to the first element greater than @p __val,
2055	* or end() if no elements are greater than @p __val.
2056	* @ingroup binary_search_algorithms
2057	*/
2058	template<typename _ForwardIterator, typename _Tp>
2059	_GLIBCXX20_CONSTEXPR
2060	inline _ForwardIterator
2061	upper_bound(_ForwardIterator __first, _ForwardIterator __last,
2062	const _Tp& __val)
2063	{
2064	// concept requirements
2065	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
2066	__glibcxx_function_requires(_LessThanOpConcept<
2067	_Tp, typename iterator_traits<_ForwardIterator>::value_type>)
2068	__glibcxx_requires_partitioned_upper(__first, __last, __val);
2069
2070	return std::__upper_bound(__first, __last, __val,
2071	__gnu_cxx::__ops::__val_less_iter());
2072	}
2073
2074	/**
2075	* @brief Finds the last position in which @p __val could be inserted
2076	* without changing the ordering.
2077	* @ingroup binary_search_algorithms
2078	* @param __first An iterator.
2079	* @param __last Another iterator.
2080	* @param __val The search term.
2081	* @param __comp A functor to use for comparisons.
2082	* @return An iterator pointing to the first element greater than @p __val,
2083	* or end() if no elements are greater than @p __val.
2084	* @ingroup binary_search_algorithms
2085	*
2086	* The comparison function should have the same effects on ordering as
2087	* the function used for the initial sort.
2088	*/
2089	template<typename _ForwardIterator, typename _Tp, typename _Compare>
2090	_GLIBCXX20_CONSTEXPR
2091	inline _ForwardIterator
2092	upper_bound(_ForwardIterator __first, _ForwardIterator __last,
2093	const _Tp& __val, _Compare __comp)
2094	{
2095	// concept requirements
2096	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
2097	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
2098	_Tp, typename iterator_traits<_ForwardIterator>::value_type>)
2099	__glibcxx_requires_partitioned_upper_pred(__first, __last,
2100	__val, __comp);
2101
2102	return std::__upper_bound(__first, __last, __val,
2103	__gnu_cxx::__ops::__val_comp_iter(__comp));
2104	}
2105
2106	template<typename _ForwardIterator, typename _Tp,
2107	typename _CompareItTp, typename _CompareTpIt>
2108	_GLIBCXX20_CONSTEXPR
2109	pair<_ForwardIterator, _ForwardIterator>
2110	__equal_range(_ForwardIterator __first, _ForwardIterator __last,
2111	const _Tp& __val,
2112	_CompareItTp __comp_it_val, _CompareTpIt __comp_val_it)
2113	{
2114	typedef typename iterator_traits<_ForwardIterator>::difference_type
2115	_DistanceType;
2116
2117	_DistanceType __len = std::distance(__first, __last);
2118
2119	while (__len > `0`)
2120	{
2121	_DistanceType __half = __len >> `1`;
2122	_ForwardIterator __middle = __first;
2123	std::advance(__middle, __half);
2124	if (__comp_it_val(__middle, __val))
2125	{
2126	__first = __middle;
2127	++__first;
2128	__len = __len - __half - `1`;
2129	}
2130	else if (__comp_val_it(__val, __middle))
2131	__len = __half;
2132	else
2133	{
2134	_ForwardIterator __left
2135	= std::__lower_bound(__first, __middle, __val, __comp_it_val);
2136	std::advance(__first, __len);
2137	_ForwardIterator __right
2138	= std::__upper_bound(++__middle, __first, __val, __comp_val_it);
2139	return pair<_ForwardIterator, _ForwardIterator>(__left, __right);
2140	}
2141	}
2142	return pair<_ForwardIterator, _ForwardIterator>(__first, __first);
2143	}
2144
2145	/**
2146	* @brief Finds the largest subrange in which @p __val could be inserted
2147	* at any place in it without changing the ordering.
2148	* @ingroup binary_search_algorithms
2149	* @param __first An iterator.
2150	* @param __last Another iterator.
2151	* @param __val The search term.
2152	* @return An pair of iterators defining the subrange.
2153	* @ingroup binary_search_algorithms
2154	*
2155	* This is equivalent to
2156	* @code
2157	* std::make_pair(lower_bound(__first, __last, __val),
2158	* upper_bound(__first, __last, __val))
2159	* @endcode
2160	* but does not actually call those functions.
2161	*/
2162	template<typename _ForwardIterator, typename _Tp>
2163	_GLIBCXX20_CONSTEXPR
2164	inline pair<_ForwardIterator, _ForwardIterator>
2165	equal_range(_ForwardIterator __first, _ForwardIterator __last,
2166	const _Tp& __val)
2167	{
2168	// concept requirements
2169	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
2170	__glibcxx_function_requires(_LessThanOpConcept<
2171	typename iterator_traits<_ForwardIterator>::value_type, _Tp>)
2172	__glibcxx_function_requires(_LessThanOpConcept<
2173	_Tp, typename iterator_traits<_ForwardIterator>::value_type>)
2174	__glibcxx_requires_partitioned_lower(__first, __last, __val);
2175	__glibcxx_requires_partitioned_upper(__first, __last, __val);
2176
2177	return std::__equal_range(__first, __last, __val,
2178	__gnu_cxx::__ops::__iter_less_val(),
2179	__gnu_cxx::__ops::__val_less_iter());
2180	}
2181
2182	/**
2183	* @brief Finds the largest subrange in which @p __val could be inserted
2184	* at any place in it without changing the ordering.
2185	* @param __first An iterator.
2186	* @param __last Another iterator.
2187	* @param __val The search term.
2188	* @param __comp A functor to use for comparisons.
2189	* @return An pair of iterators defining the subrange.
2190	* @ingroup binary_search_algorithms
2191	*
2192	* This is equivalent to
2193	* @code
2194	* std::make_pair(lower_bound(__first, __last, __val, __comp),
2195	* upper_bound(__first, __last, __val, __comp))
2196	* @endcode
2197	* but does not actually call those functions.
2198	*/
2199	template<typename _ForwardIterator, typename _Tp, typename _Compare>
2200	_GLIBCXX20_CONSTEXPR
2201	inline pair<_ForwardIterator, _ForwardIterator>
2202	equal_range(_ForwardIterator __first, _ForwardIterator __last,
2203	const _Tp& __val, _Compare __comp)
2204	{
2205	// concept requirements
2206	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
2207	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
2208	typename iterator_traits<_ForwardIterator>::value_type, _Tp>)
2209	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
2210	_Tp, typename iterator_traits<_ForwardIterator>::value_type>)
2211	__glibcxx_requires_partitioned_lower_pred(__first, __last,
2212	__val, __comp);
2213	__glibcxx_requires_partitioned_upper_pred(__first, __last,
2214	__val, __comp);
2215
2216	return std::__equal_range(__first, __last, __val,
2217	__gnu_cxx::__ops::__iter_comp_val(__comp),
2218	__gnu_cxx::__ops::__val_comp_iter(__comp));
2219	}
2220
2221	/**
2222	* @brief Determines whether an element exists in a range.
2223	* @ingroup binary_search_algorithms
2224	* @param __first An iterator.
2225	* @param __last Another iterator.
2226	* @param __val The search term.
2227	* @return True if @p __val (or its equivalent) is in [@p
2228	* __first,@p __last ].
2229	*
2230	* Note that this does not actually return an iterator to @p __val. For
2231	* that, use std::find or a container's specialized find member functions.
2232	*/
2233	template<typename _ForwardIterator, typename _Tp>
2234	_GLIBCXX20_CONSTEXPR
2235	bool
2236	binary_search(_ForwardIterator __first, _ForwardIterator __last,
2237	const _Tp& __val)
2238	{
2239	// concept requirements
2240	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
2241	__glibcxx_function_requires(_LessThanOpConcept<
2242	_Tp, typename iterator_traits<_ForwardIterator>::value_type>)
2243	__glibcxx_requires_partitioned_lower(__first, __last, __val);
2244	__glibcxx_requires_partitioned_upper(__first, __last, __val);
2245
2246	_ForwardIterator __i
2247	= std::__lower_bound(__first, __last, __val,
2248	__gnu_cxx::__ops::__iter_less_val());
2249	return __i != __last && !(__val < *__i);
2250	}
2251
2252	/**
2253	* @brief Determines whether an element exists in a range.
2254	* @ingroup binary_search_algorithms
2255	* @param __first An iterator.
2256	* @param __last Another iterator.
2257	* @param __val The search term.
2258	* @param __comp A functor to use for comparisons.
2259	* @return True if @p __val (or its equivalent) is in @p [__first,__last].
2260	*
2261	* Note that this does not actually return an iterator to @p __val. For
2262	* that, use std::find or a container's specialized find member functions.
2263	*
2264	* The comparison function should have the same effects on ordering as
2265	* the function used for the initial sort.
2266	*/
2267	template<typename _ForwardIterator, typename _Tp, typename _Compare>
2268	_GLIBCXX20_CONSTEXPR
2269	bool
2270	binary_search(_ForwardIterator __first, _ForwardIterator __last,
2271	const _Tp& __val, _Compare __comp)
2272	{
2273	// concept requirements
2274	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
2275	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
2276	_Tp, typename iterator_traits<_ForwardIterator>::value_type>)
2277	__glibcxx_requires_partitioned_lower_pred(__first, __last,
2278	__val, __comp);
2279	__glibcxx_requires_partitioned_upper_pred(__first, __last,
2280	__val, __comp);
2281
2282	_ForwardIterator __i
2283	= std::__lower_bound(__first, __last, __val,
2284	__gnu_cxx::__ops::__iter_comp_val(__comp));
2285	return __i != __last && !bool(__comp(__val, *__i));
2286	}
2287
2288	// merge
2289
2290	/// This is a helper function for the __merge_adaptive routines.
2291	template<typename _InputIterator1, typename _InputIterator2,
2292	typename _OutputIterator, typename _Compare>
2293	void
2294	__move_merge_adaptive(_InputIterator1 __first1, _InputIterator1 __last1,
2295	_InputIterator2 __first2, _InputIterator2 __last2,
2296	_OutputIterator __result, _Compare __comp)
2297	{
2298	while (__first1 != __last1 && __first2 != __last2)
2299	{
2300	if (__comp(__first2, __first1))
2301	{
2302	__result = _GLIBCXX_MOVE(__first2);
2303	++__first2;
2304	}
2305	else
2306	{
2307	__result = _GLIBCXX_MOVE(__first1);
2308	++__first1;
2309	}
2310	++__result;
2311	}
2312	if (__first1 != __last1)
2313	_GLIBCXX_MOVE3(__first1, __last1, __result);
2314	}
2315
2316	/// This is a helper function for the __merge_adaptive routines.
2317	template<typename _BidirectionalIterator1, typename _BidirectionalIterator2,
2318	typename _BidirectionalIterator3, typename _Compare>
2319	void
2320	__move_merge_adaptive_backward(_BidirectionalIterator1 __first1,
2321	_BidirectionalIterator1 __last1,
2322	_BidirectionalIterator2 __first2,
2323	_BidirectionalIterator2 __last2,
2324	_BidirectionalIterator3 __result,
2325	_Compare __comp)
2326	{
2327	if (__first1 == __last1)
2328	{
2329	_GLIBCXX_MOVE_BACKWARD3(__first2, __last2, __result);
2330	return;
2331	}
2332	else if (__first2 == __last2)
2333	return;
2334
2335	--__last1;
2336	--__last2;
2337	while (true)
2338	{
2339	if (__comp(__last2, __last1))
2340	{
2341	--__result = _GLIBCXX_MOVE(__last1);
2342	if (__first1 == __last1)
2343	{
2344	_GLIBCXX_MOVE_BACKWARD3(__first2, ++__last2, __result);
2345	return;
2346	}
2347	--__last1;
2348	}
2349	else
2350	{
2351	--__result = _GLIBCXX_MOVE(__last2);
2352	if (__first2 == __last2)
2353	return;
2354	--__last2;
2355	}
2356	}
2357	}
2358
2359	/// This is a helper function for the merge routines.
2360	template<typename _BidirectionalIterator1, typename _BidirectionalIterator2,
2361	typename _Distance>
2362	_BidirectionalIterator1
2363	__rotate_adaptive(_BidirectionalIterator1 __first,
2364	_BidirectionalIterator1 __middle,
2365	_BidirectionalIterator1 __last,
2366	_Distance __len1, _Distance __len2,
2367	_BidirectionalIterator2 __buffer,
2368	_Distance __buffer_size)
2369	{
2370	_BidirectionalIterator2 __buffer_end;
2371	if (__len1 > __len2 && __len2 <= __buffer_size)
2372	{
2373	if (__len2)
2374	{
2375	__buffer_end = _GLIBCXX_MOVE3(__middle, __last, __buffer);
2376	_GLIBCXX_MOVE_BACKWARD3(__first, __middle, __last);
2377	return _GLIBCXX_MOVE3(__buffer, __buffer_end, __first);
2378	}
2379	else
2380	return __first;
2381	}
2382	else if (__len1 <= __buffer_size)
2383	{
2384	if (__len1)
2385	{
2386	__buffer_end = _GLIBCXX_MOVE3(__first, __middle, __buffer);
2387	_GLIBCXX_MOVE3(__middle, __last, __first);
2388	return _GLIBCXX_MOVE_BACKWARD3(__buffer, __buffer_end, __last);
2389	}
2390	else
2391	return __last;
2392	}
2393	else
2394	return std::rotate(__first, __middle, __last);
2395	}
2396
2397	/// This is a helper function for the merge routines.
2398	template<typename _BidirectionalIterator, typename _Distance,
2399	typename _Pointer, typename _Compare>
2400	void
2401	__merge_adaptive(_BidirectionalIterator __first,
2402	_BidirectionalIterator __middle,
2403	_BidirectionalIterator __last,
2404	_Distance __len1, _Distance __len2,
2405	_Pointer __buffer, _Compare __comp)
2406	{
2407	if (__len1 <= __len2)
2408	{
2409	_Pointer __buffer_end = _GLIBCXX_MOVE3(__first, __middle, __buffer);
2410	std::__move_merge_adaptive(__buffer, __buffer_end, __middle, __last,
2411	__first, __comp);
2412	}
2413	else
2414	{
2415	_Pointer __buffer_end = _GLIBCXX_MOVE3(__middle, __last, __buffer);
2416	std::__move_merge_adaptive_backward(__first, __middle, __buffer,
2417	__buffer_end, __last, __comp);
2418	}
2419	}
2420
2421	template<typename _BidirectionalIterator, typename _Distance,
2422	typename _Pointer, typename _Compare>
2423	void
2424	__merge_adaptive_resize(_BidirectionalIterator __first,
2425	_BidirectionalIterator __middle,
2426	_BidirectionalIterator __last,
2427	_Distance __len1, _Distance __len2,
2428	_Pointer __buffer, _Distance __buffer_size,
2429	_Compare __comp)
2430	{
2431	if (__len1 <= __buffer_size \|\| __len2 <= __buffer_size)
2432	std::__merge_adaptive(__first, __middle, __last,
2433	__len1, __len2, __buffer, __comp);
2434	else
2435	{
2436	_BidirectionalIterator __first_cut = __first;
2437	_BidirectionalIterator __second_cut = __middle;
2438	_Distance __len11 = `0`;
2439	_Distance __len22 = `0`;
2440	if (__len1 > __len2)
2441	{
2442	__len11 = __len1 / `2`;
2443	std::advance(__first_cut, __len11);
2444	__second_cut
2445	= std::__lower_bound(__middle, __last, *__first_cut,
2446	__gnu_cxx::__ops::__iter_comp_val(__comp));
2447	__len22 = std::distance(__middle, __second_cut);
2448	}
2449	else
2450	{
2451	__len22 = __len2 / `2`;
2452	std::advance(__second_cut, __len22);
2453	__first_cut
2454	= std::__upper_bound(__first, __middle, *__second_cut,
2455	__gnu_cxx::__ops::__val_comp_iter(__comp));
2456	__len11 = std::distance(__first, __first_cut);
2457	}
2458
2459	_BidirectionalIterator __new_middle
2460	= std::__rotate_adaptive(__first_cut, __middle, __second_cut,
2461	_Distance(__len1 - __len11), __len22,
2462	__buffer, __buffer_size);
2463	std::__merge_adaptive_resize(__first, __first_cut, __new_middle,
2464	__len11, __len22,
2465	__buffer, __buffer_size, __comp);
2466	std::__merge_adaptive_resize(__new_middle, __second_cut, __last,
2467	_Distance(__len1 - __len11),
2468	_Distance(__len2 - __len22),
2469	__buffer, __buffer_size, __comp);
2470	}
2471	}
2472
2473	/// This is a helper function for the merge routines.
2474	template<typename _BidirectionalIterator, typename _Distance,
2475	typename _Compare>
2476	void
2477	__merge_without_buffer(_BidirectionalIterator __first,
2478	_BidirectionalIterator __middle,
2479	_BidirectionalIterator __last,
2480	_Distance __len1, _Distance __len2,
2481	_Compare __comp)
2482	{
2483	if (__len1 == `0` \|\| __len2 == `0`)
2484	return;
2485
2486	if (__len1 + __len2 == `2`)
2487	{
2488	if (__comp(__middle, __first))
2489	std::iter_swap(__first, __middle);
2490	return;
2491	}
2492
2493	_BidirectionalIterator __first_cut = __first;
2494	_BidirectionalIterator __second_cut = __middle;
2495	_Distance __len11 = `0`;
2496	_Distance __len22 = `0`;
2497	if (__len1 > __len2)
2498	{
2499	__len11 = __len1 / `2`;
2500	std::advance(__first_cut, __len11);
2501	__second_cut
2502	= std::__lower_bound(__middle, __last, *__first_cut,
2503	__gnu_cxx::__ops::__iter_comp_val(__comp));
2504	__len22 = std::distance(__middle, __second_cut);
2505	}
2506	else
2507	{
2508	__len22 = __len2 / `2`;
2509	std::advance(__second_cut, __len22);
2510	__first_cut
2511	= std::__upper_bound(__first, __middle, *__second_cut,
2512	__gnu_cxx::__ops::__val_comp_iter(__comp));
2513	__len11 = std::distance(__first, __first_cut);
2514	}
2515
2516	_BidirectionalIterator __new_middle
2517	= std::rotate(__first_cut, __middle, __second_cut);
2518	std::__merge_without_buffer(__first, __first_cut, __new_middle,
2519	__len11, __len22, __comp);
2520	std::__merge_without_buffer(__new_middle, __second_cut, __last,
2521	__len1 - __len11, __len2 - __len22, __comp);
2522	}
2523
2524	template<typename _BidirectionalIterator, typename _Compare>
2525	void
2526	__inplace_merge(_BidirectionalIterator __first,
2527	_BidirectionalIterator __middle,
2528	_BidirectionalIterator __last,
2529	_Compare __comp)
2530	{
2531	typedef typename iterator_traits<_BidirectionalIterator>::value_type
2532	_ValueType;
2533	typedef typename iterator_traits<_BidirectionalIterator>::difference_type
2534	_DistanceType;
2535
2536	if (__first == __middle \|\| __middle == __last)
2537	return;
2538
2539	const _DistanceType __len1 = std::distance(__first, __middle);
2540	const _DistanceType __len2 = std::distance(__middle, __last);
2541
2542	#if _GLIBCXX_HOSTED
2543	typedef _Temporary_buffer<_BidirectionalIterator, _ValueType> _TmpBuf;
2544	// __merge_adaptive will use a buffer for the smaller of
2545	// [first,middle) and [middle,last).
2546	_TmpBuf __buf(__first, std::min(__len1, __len2));
2547
2548	if (__builtin_expect(__buf.size() == __buf.requested_size(), true))
2549	std::__merge_adaptive
2550	(__first, __middle, __last, __len1, __len2, __buf.begin(), __comp);
2551	else if (__builtin_expect(__buf.begin() == `0`, false))
2552	std::__merge_without_buffer
2553	(__first, __middle, __last, __len1, __len2, __comp);
2554	else
2555	std::__merge_adaptive_resize
2556	(__first, __middle, __last, __len1, __len2, __buf.begin(),
2557	_DistanceType(__buf.size()), __comp);
2558	#else
2559	std::__merge_without_buffer
2560	(__first, __middle, __last, __len1, __len2, __comp);
2561	#endif
2562	}
2563
2564	/**
2565	* @brief Merges two sorted ranges in place.
2566	* @ingroup sorting_algorithms
2567	* @param __first An iterator.
2568	* @param __middle Another iterator.
2569	* @param __last Another iterator.
2570	* @return Nothing.
2571	*
2572	* Merges two sorted and consecutive ranges, [__first,__middle) and
2573	* [__middle,__last), and puts the result in [__first,__last). The
2574	* output will be sorted. The sort is @e stable, that is, for
2575	* equivalent elements in the two ranges, elements from the first
2576	* range will always come before elements from the second.
2577	*
2578	* If enough additional memory is available, this takes (__last-__first)-1
2579	* comparisons. Otherwise an NlogN algorithm is used, where N is
2580	* distance(__first,__last).
2581	*/
2582	template<typename _BidirectionalIterator>
2583	inline void
2584	inplace_merge(_BidirectionalIterator __first,
2585	_BidirectionalIterator __middle,
2586	_BidirectionalIterator __last)
2587	{
2588	// concept requirements
2589	__glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<
2590	_BidirectionalIterator>)
2591	__glibcxx_function_requires(_LessThanComparableConcept<
2592	typename iterator_traits<_BidirectionalIterator>::value_type>)
2593	__glibcxx_requires_sorted(__first, __middle);
2594	__glibcxx_requires_sorted(__middle, __last);
2595	__glibcxx_requires_irreflexive(__first, __last);
2596
2597	std::__inplace_merge(__first, __middle, __last,
2598	__gnu_cxx::__ops::__iter_less_iter());
2599	}
2600
2601	/**
2602	* @brief Merges two sorted ranges in place.
2603	* @ingroup sorting_algorithms
2604	* @param __first An iterator.
2605	* @param __middle Another iterator.
2606	* @param __last Another iterator.
2607	* @param __comp A functor to use for comparisons.
2608	* @return Nothing.
2609	*
2610	* Merges two sorted and consecutive ranges, [__first,__middle) and
2611	* [middle,last), and puts the result in [__first,__last). The output will
2612	* be sorted. The sort is @e stable, that is, for equivalent
2613	* elements in the two ranges, elements from the first range will always
2614	* come before elements from the second.
2615	*
2616	* If enough additional memory is available, this takes (__last-__first)-1
2617	* comparisons. Otherwise an NlogN algorithm is used, where N is
2618	* distance(__first,__last).
2619	*
2620	* The comparison function should have the same effects on ordering as
2621	* the function used for the initial sort.
2622	*/
2623	template<typename _BidirectionalIterator, typename _Compare>
2624	inline void
2625	inplace_merge(_BidirectionalIterator __first,
2626	_BidirectionalIterator __middle,
2627	_BidirectionalIterator __last,
2628	_Compare __comp)
2629	{
2630	// concept requirements
2631	__glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<
2632	_BidirectionalIterator>)
2633	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
2634	typename iterator_traits<_BidirectionalIterator>::value_type,
2635	typename iterator_traits<_BidirectionalIterator>::value_type>)
2636	__glibcxx_requires_sorted_pred(__first, __middle, __comp);
2637	__glibcxx_requires_sorted_pred(__middle, __last, __comp);
2638	__glibcxx_requires_irreflexive_pred(__first, __last, __comp);
2639
2640	std::__inplace_merge(__first, __middle, __last,
2641	__gnu_cxx::__ops::__iter_comp_iter(__comp));
2642	}
2643
2644
2645	/// This is a helper function for the __merge_sort_loop routines.
2646	template<typename _InputIterator, typename _OutputIterator,
2647	typename _Compare>
2648	_OutputIterator
2649	__move_merge(_InputIterator __first1, _InputIterator __last1,
2650	_InputIterator __first2, _InputIterator __last2,
2651	_OutputIterator __result, _Compare __comp)
2652	{
2653	while (__first1 != __last1 && __first2 != __last2)
2654	{
2655	if (__comp(__first2, __first1))
2656	{
2657	__result = _GLIBCXX_MOVE(__first2);
2658	++__first2;
2659	}
2660	else
2661	{
2662	__result = _GLIBCXX_MOVE(__first1);
2663	++__first1;
2664	}
2665	++__result;
2666	}
2667	return _GLIBCXX_MOVE3(__first2, __last2,
2668	_GLIBCXX_MOVE3(__first1, __last1,
2669	__result));
2670	}
2671
2672	template<typename _RandomAccessIterator1, typename _RandomAccessIterator2,
2673	typename _Distance, typename _Compare>
2674	void
2675	__merge_sort_loop(_RandomAccessIterator1 __first,
2676	_RandomAccessIterator1 __last,
2677	_RandomAccessIterator2 __result, _Distance __step_size,
2678	_Compare __comp)
2679	{
2680	const _Distance __two_step = `2` * __step_size;
2681
2682	while (__last - __first >= __two_step)
2683	{
2684	__result = std::__move_merge(__first, __first + __step_size,
2685	__first + __step_size,
2686	__first + __two_step,
2687	__result, __comp);
2688	__first += __two_step;
2689	}
2690	__step_size = std::min(_Distance(__last - __first), __step_size);
2691
2692	std::__move_merge(__first, __first + __step_size,
2693	__first + __step_size, __last, __result, __comp);
2694	}
2695
2696	template<typename _RandomAccessIterator, typename _Distance,
2697	typename _Compare>
2698	_GLIBCXX20_CONSTEXPR
2699	void
2700	__chunk_insertion_sort(_RandomAccessIterator __first,
2701	_RandomAccessIterator __last,
2702	_Distance __chunk_size, _Compare __comp)
2703	{
2704	while (__last - __first >= __chunk_size)
2705	{
2706	std::__insertion_sort(__first, __first + __chunk_size, __comp);
2707	__first += __chunk_size;
2708	}
2709	std::__insertion_sort(__first, __last, __comp);
2710	}
2711
2712	enum { _S_chunk_size = `7` };
2713
2714	template<typename _RandomAccessIterator, typename _Pointer, typename _Compare>
2715	void
2716	__merge_sort_with_buffer(_RandomAccessIterator __first,
2717	_RandomAccessIterator __last,
2718	_Pointer __buffer, _Compare __comp)
2719	{
2720	typedef typename iterator_traits<_RandomAccessIterator>::difference_type
2721	_Distance;
2722
2723	const _Distance __len = __last - __first;
2724	const _Pointer __buffer_last = __buffer + __len;
2725
2726	_Distance __step_size = _S_chunk_size;
2727	std::__chunk_insertion_sort(__first, __last, __step_size, __comp);
2728
2729	while (__step_size < __len)
2730	{
2731	std::__merge_sort_loop(__first, __last, __buffer,
2732	__step_size, __comp);
2733	__step_size *= `2`;
2734	std::__merge_sort_loop(__buffer, __buffer_last, __first,
2735	__step_size, __comp);
2736	__step_size *= `2`;
2737	}
2738	}
2739
2740	template<typename _RandomAccessIterator, typename _Pointer, typename _Compare>
2741	void
2742	__stable_sort_adaptive(_RandomAccessIterator __first,
2743	_RandomAccessIterator __middle,
2744	_RandomAccessIterator __last,
2745	_Pointer __buffer, _Compare __comp)
2746	{
2747	std::__merge_sort_with_buffer(__first, __middle, __buffer, __comp);
2748	std::__merge_sort_with_buffer(__middle, __last, __buffer, __comp);
2749
2750	std::__merge_adaptive(__first, __middle, __last,
2751	__middle - __first, __last - __middle,
2752	__buffer, __comp);
2753	}
2754
2755	template<typename _RandomAccessIterator, typename _Pointer,
2756	typename _Distance, typename _Compare>
2757	void
2758	__stable_sort_adaptive_resize(_RandomAccessIterator __first,
2759	_RandomAccessIterator __last,
2760	_Pointer __buffer, _Distance __buffer_size,
2761	_Compare __comp)
2762	{
2763	const _Distance __len = (__last - __first + `1`) / `2`;
2764	const _RandomAccessIterator __middle = __first + __len;
2765	if (__len > __buffer_size)
2766	{
2767	std::__stable_sort_adaptive_resize(__first, __middle, __buffer,
2768	__buffer_size, __comp);
2769	std::__stable_sort_adaptive_resize(__middle, __last, __buffer,
2770	__buffer_size, __comp);
2771	std::__merge_adaptive_resize(__first, __middle, __last,
2772	_Distance(__middle - __first),
2773	_Distance(__last - __middle),
2774	__buffer, __buffer_size,
2775	__comp);
2776	}
2777	else
2778	std::__stable_sort_adaptive(__first, __middle, __last,
2779	__buffer, __comp);
2780	}
2781
2782	/// This is a helper function for the stable sorting routines.
2783	template<typename _RandomAccessIterator, typename _Compare>
2784	void
2785	__inplace_stable_sort(_RandomAccessIterator __first,
2786	_RandomAccessIterator __last, _Compare __comp)
2787	{
2788	if (__last - __first < `15`)
2789	{
2790	std::__insertion_sort(__first, __last, __comp);
2791	return;
2792	}
2793	_RandomAccessIterator __middle = __first + (__last - __first) / `2`;
2794	std::__inplace_stable_sort(__first, __middle, __comp);
2795	std::__inplace_stable_sort(__middle, __last, __comp);
2796	std::__merge_without_buffer(__first, __middle, __last,
2797	__middle - __first,
2798	__last - __middle,
2799	__comp);
2800	}
2801
2802	// stable_sort
2803
2804	// Set algorithms: includes, set_union, set_intersection, set_difference,
2805	// set_symmetric_difference. All of these algorithms have the precondition
2806	// that their input ranges are sorted and the postcondition that their output
2807	// ranges are sorted.
2808
2809	template<typename _InputIterator1, typename _InputIterator2,
2810	typename _Compare>
2811	_GLIBCXX20_CONSTEXPR
2812	bool
2813	__includes(_InputIterator1 __first1, _InputIterator1 __last1,
2814	_InputIterator2 __first2, _InputIterator2 __last2,
2815	_Compare __comp)
2816	{
2817	while (__first1 != __last1 && __first2 != __last2)
2818	{
2819	if (__comp(__first2, __first1))
2820	return false;
2821	if (!__comp(__first1, __first2))
2822	++__first2;
2823	++__first1;
2824	}
2825
2826	return __first2 == __last2;
2827	}
2828
2829	/**
2830	* @brief Determines whether all elements of a sequence exists in a range.
2831	* @param __first1 Start of search range.
2832	* @param __last1 End of search range.
2833	* @param __first2 Start of sequence
2834	* @param __last2 End of sequence.
2835	* @return True if each element in [__first2,__last2) is contained in order
2836	* within [__first1,__last1). False otherwise.
2837	* @ingroup set_algorithms
2838	*
2839	* This operation expects both [__first1,__last1) and
2840	* [__first2,__last2) to be sorted. Searches for the presence of
2841	* each element in [__first2,__last2) within [__first1,__last1).
2842	* The iterators over each range only move forward, so this is a
2843	* linear algorithm. If an element in [__first2,__last2) is not
2844	* found before the search iterator reaches @p __last2, false is
2845	* returned.
2846	*/
2847	template<typename _InputIterator1, typename _InputIterator2>
2848	_GLIBCXX20_CONSTEXPR
2849	inline bool
2850	includes(_InputIterator1 __first1, _InputIterator1 __last1,
2851	_InputIterator2 __first2, _InputIterator2 __last2)
2852	{
2853	// concept requirements
2854	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
2855	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
2856	__glibcxx_function_requires(_LessThanOpConcept<
2857	typename iterator_traits<_InputIterator1>::value_type,
2858	typename iterator_traits<_InputIterator2>::value_type>)
2859	__glibcxx_function_requires(_LessThanOpConcept<
2860	typename iterator_traits<_InputIterator2>::value_type,
2861	typename iterator_traits<_InputIterator1>::value_type>)
2862	__glibcxx_requires_sorted_set(__first1, __last1, __first2);
2863	__glibcxx_requires_sorted_set(__first2, __last2, __first1);
2864	__glibcxx_requires_irreflexive2(__first1, __last1);
2865	__glibcxx_requires_irreflexive2(__first2, __last2);
2866
2867	return std::__includes(__first1, __last1, __first2, __last2,
2868	__gnu_cxx::__ops::__iter_less_iter());
2869	}
2870
2871	/**
2872	* @brief Determines whether all elements of a sequence exists in a range
2873	* using comparison.
2874	* @ingroup set_algorithms
2875	* @param __first1 Start of search range.
2876	* @param __last1 End of search range.
2877	* @param __first2 Start of sequence
2878	* @param __last2 End of sequence.
2879	* @param __comp Comparison function to use.
2880	* @return True if each element in [__first2,__last2) is contained
2881	* in order within [__first1,__last1) according to comp. False
2882	* otherwise. @ingroup set_algorithms
2883	*
2884	* This operation expects both [__first1,__last1) and
2885	* [__first2,__last2) to be sorted. Searches for the presence of
2886	* each element in [__first2,__last2) within [__first1,__last1),
2887	* using comp to decide. The iterators over each range only move
2888	* forward, so this is a linear algorithm. If an element in
2889	* [__first2,__last2) is not found before the search iterator
2890	* reaches @p __last2, false is returned.
2891	*/
2892	template<typename _InputIterator1, typename _InputIterator2,
2893	typename _Compare>
2894	_GLIBCXX20_CONSTEXPR
2895	inline bool
2896	includes(_InputIterator1 __first1, _InputIterator1 __last1,
2897	_InputIterator2 __first2, _InputIterator2 __last2,
2898	_Compare __comp)
2899	{
2900	// concept requirements
2901	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
2902	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
2903	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
2904	typename iterator_traits<_InputIterator1>::value_type,
2905	typename iterator_traits<_InputIterator2>::value_type>)
2906	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
2907	typename iterator_traits<_InputIterator2>::value_type,
2908	typename iterator_traits<_InputIterator1>::value_type>)
2909	__glibcxx_requires_sorted_set_pred(__first1, __last1, __first2, __comp);
2910	__glibcxx_requires_sorted_set_pred(__first2, __last2, __first1, __comp);
2911	__glibcxx_requires_irreflexive_pred2(__first1, __last1, __comp);
2912	__glibcxx_requires_irreflexive_pred2(__first2, __last2, __comp);
2913
2914	return std::__includes(__first1, __last1, __first2, __last2,
2915	__gnu_cxx::__ops::__iter_comp_iter(__comp));
2916	}
2917
2918	// nth_element
2919	// merge
2920	// set_difference
2921	// set_intersection
2922	// set_union
2923	// stable_sort
2924	// set_symmetric_difference
2925	// min_element
2926	// max_element
2927
2928	template<typename _BidirectionalIterator, typename _Compare>
2929	_GLIBCXX20_CONSTEXPR
2930	bool
2931	__next_permutation(_BidirectionalIterator __first,
2932	_BidirectionalIterator __last, _Compare __comp)
2933	{
2934	if (__first == __last)
2935	return false;
2936	_BidirectionalIterator __i = __first;
2937	++__i;
2938	if (__i == __last)
2939	return false;
2940	__i = __last;
2941	--__i;
2942
2943	for(;;)
2944	{
2945	_BidirectionalIterator __ii = __i;
2946	--__i;
2947	if (__comp(__i, __ii))
2948	{
2949	_BidirectionalIterator __j = __last;
2950	while (!__comp(__i, --__j))
2951	{}
2952	std::iter_swap(__i, __j);
2953	std::__reverse(__ii, __last,
2954	std::__iterator_category(__first));
2955	return true;
2956	}
2957	if (__i == __first)
2958	{
2959	std::__reverse(__first, __last,
2960	std::__iterator_category(__first));
2961	return false;
2962	}
2963	}
2964	}
2965
2966	/**
2967	* @brief Permute range into the next @e dictionary ordering.
2968	* @ingroup sorting_algorithms
2969	* @param __first Start of range.
2970	* @param __last End of range.
2971	* @return False if wrapped to first permutation, true otherwise.
2972	*
2973	* Treats all permutations of the range as a set of @e dictionary sorted
2974	* sequences. Permutes the current sequence into the next one of this set.
2975	* Returns true if there are more sequences to generate. If the sequence
2976	* is the largest of the set, the smallest is generated and false returned.
2977	*/
2978	template<typename _BidirectionalIterator>
2979	_GLIBCXX20_CONSTEXPR
2980	inline bool
2981	next_permutation(_BidirectionalIterator __first,
2982	_BidirectionalIterator __last)
2983	{
2984	// concept requirements
2985	__glibcxx_function_requires(_BidirectionalIteratorConcept<
2986	_BidirectionalIterator>)
2987	__glibcxx_function_requires(_LessThanComparableConcept<
2988	typename iterator_traits<_BidirectionalIterator>::value_type>)
2989	__glibcxx_requires_valid_range(__first, __last);
2990	__glibcxx_requires_irreflexive(__first, __last);
2991
2992	return std::__next_permutation
2993	(__first, __last, __gnu_cxx::__ops::__iter_less_iter());
2994	}
2995
2996	/**
2997	* @brief Permute range into the next @e dictionary ordering using
2998	* comparison functor.
2999	* @ingroup sorting_algorithms
3000	* @param __first Start of range.
3001	* @param __last End of range.
3002	* @param __comp A comparison functor.
3003	* @return False if wrapped to first permutation, true otherwise.
3004	*
3005	* Treats all permutations of the range [__first,__last) as a set of
3006	* @e dictionary sorted sequences ordered by @p __comp. Permutes the current
3007	* sequence into the next one of this set. Returns true if there are more
3008	* sequences to generate. If the sequence is the largest of the set, the
3009	* smallest is generated and false returned.
3010	*/
3011	template<typename _BidirectionalIterator, typename _Compare>
3012	_GLIBCXX20_CONSTEXPR
3013	inline bool
3014	next_permutation(_BidirectionalIterator __first,
3015	_BidirectionalIterator __last, _Compare __comp)
3016	{
3017	// concept requirements
3018	__glibcxx_function_requires(_BidirectionalIteratorConcept<
3019	_BidirectionalIterator>)
3020	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
3021	typename iterator_traits<_BidirectionalIterator>::value_type,
3022	typename iterator_traits<_BidirectionalIterator>::value_type>)
3023	__glibcxx_requires_valid_range(__first, __last);
3024	__glibcxx_requires_irreflexive_pred(__first, __last, __comp);
3025
3026	return std::__next_permutation
3027	(__first, __last, __gnu_cxx::__ops::__iter_comp_iter(__comp));
3028	}
3029
3030	template<typename _BidirectionalIterator, typename _Compare>
3031	_GLIBCXX20_CONSTEXPR
3032	bool
3033	__prev_permutation(_BidirectionalIterator __first,
3034	_BidirectionalIterator __last, _Compare __comp)
3035	{
3036	if (__first == __last)
3037	return false;
3038	_BidirectionalIterator __i = __first;
3039	++__i;
3040	if (__i == __last)
3041	return false;
3042	__i = __last;
3043	--__i;
3044
3045	for(;;)
3046	{
3047	_BidirectionalIterator __ii = __i;
3048	--__i;
3049	if (__comp(__ii, __i))
3050	{
3051	_BidirectionalIterator __j = __last;
3052	while (!__comp(--__j, __i))
3053	{}
3054	std::iter_swap(__i, __j);
3055	std::__reverse(__ii, __last,
3056	std::__iterator_category(__first));
3057	return true;
3058	}
3059	if (__i == __first)
3060	{
3061	std::__reverse(__first, __last,
3062	std::__iterator_category(__first));
3063	return false;
3064	}
3065	}
3066	}
3067
3068	/**
3069	* @brief Permute range into the previous @e dictionary ordering.
3070	* @ingroup sorting_algorithms
3071	* @param __first Start of range.
3072	* @param __last End of range.
3073	* @return False if wrapped to last permutation, true otherwise.
3074	*
3075	* Treats all permutations of the range as a set of @e dictionary sorted
3076	* sequences. Permutes the current sequence into the previous one of this
3077	* set. Returns true if there are more sequences to generate. If the
3078	* sequence is the smallest of the set, the largest is generated and false
3079	* returned.
3080	*/
3081	template<typename _BidirectionalIterator>
3082	_GLIBCXX20_CONSTEXPR
3083	inline bool
3084	prev_permutation(_BidirectionalIterator __first,
3085	_BidirectionalIterator __last)
3086	{
3087	// concept requirements
3088	__glibcxx_function_requires(_BidirectionalIteratorConcept<
3089	_BidirectionalIterator>)
3090	__glibcxx_function_requires(_LessThanComparableConcept<
3091	typename iterator_traits<_BidirectionalIterator>::value_type>)
3092	__glibcxx_requires_valid_range(__first, __last);
3093	__glibcxx_requires_irreflexive(__first, __last);
3094
3095	return std::__prev_permutation(__first, __last,
3096	__gnu_cxx::__ops::__iter_less_iter());
3097	}
3098
3099	/**
3100	* @brief Permute range into the previous @e dictionary ordering using
3101	* comparison functor.
3102	* @ingroup sorting_algorithms
3103	* @param __first Start of range.
3104	* @param __last End of range.
3105	* @param __comp A comparison functor.
3106	* @return False if wrapped to last permutation, true otherwise.
3107	*
3108	* Treats all permutations of the range [__first,__last) as a set of
3109	* @e dictionary sorted sequences ordered by @p __comp. Permutes the current
3110	* sequence into the previous one of this set. Returns true if there are
3111	* more sequences to generate. If the sequence is the smallest of the set,
3112	* the largest is generated and false returned.
3113	*/
3114	template<typename _BidirectionalIterator, typename _Compare>
3115	_GLIBCXX20_CONSTEXPR
3116	inline bool
3117	prev_permutation(_BidirectionalIterator __first,
3118	_BidirectionalIterator __last, _Compare __comp)
3119	{
3120	// concept requirements
3121	__glibcxx_function_requires(_BidirectionalIteratorConcept<
3122	_BidirectionalIterator>)
3123	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
3124	typename iterator_traits<_BidirectionalIterator>::value_type,
3125	typename iterator_traits<_BidirectionalIterator>::value_type>)
3126	__glibcxx_requires_valid_range(__first, __last);
3127	__glibcxx_requires_irreflexive_pred(__first, __last, __comp);
3128
3129	return std::__prev_permutation(__first, __last,
3130	__gnu_cxx::__ops::__iter_comp_iter(__comp));
3131	}
3132
3133	// replace
3134	// replace_if
3135
3136	template<typename _InputIterator, typename _OutputIterator,
3137	typename _Predicate, typename _Tp>
3138	_GLIBCXX20_CONSTEXPR
3139	_OutputIterator
3140	__replace_copy_if(_InputIterator __first, _InputIterator __last,
3141	_OutputIterator __result,
3142	_Predicate __pred, const _Tp& __new_value)
3143	{
3144	for (; __first != __last; ++__first, (void)++__result)
3145	if (__pred(__first))
3146	*__result = __new_value;
3147	else
3148	__result = __first;
3149	return __result;
3150	}
3151
3152	/**
3153	* @brief Copy a sequence, replacing each element of one value with another
3154	* value.
3155	* @param __first An input iterator.
3156	* @param __last An input iterator.
3157	* @param __result An output iterator.
3158	* @param __old_value The value to be replaced.
3159	* @param __new_value The replacement value.
3160	* @return The end of the output sequence, @p result+(last-first).
3161	*
3162	* Copies each element in the input range @p [__first,__last) to the
3163	* output range @p [__result,__result+(__last-__first)) replacing elements
3164	* equal to @p __old_value with @p __new_value.
3165	*/
3166	template<typename _InputIterator, typename _OutputIterator, typename _Tp>
3167	_GLIBCXX20_CONSTEXPR
3168	inline _OutputIterator
3169	replace_copy(_InputIterator __first, _InputIterator __last,
3170	_OutputIterator __result,
3171	const _Tp& __old_value, const _Tp& __new_value)
3172	{
3173	// concept requirements
3174	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
3175	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
3176	typename iterator_traits<_InputIterator>::value_type>)
3177	__glibcxx_function_requires(_EqualOpConcept<
3178	typename iterator_traits<_InputIterator>::value_type, _Tp>)
3179	__glibcxx_requires_valid_range(__first, __last);
3180
3181	return std::__replace_copy_if(__first, __last, __result,
3182	__gnu_cxx::__ops::__iter_equals_val(__old_value),
3183	__new_value);
3184	}
3185
3186	/**
3187	* @brief Copy a sequence, replacing each value for which a predicate
3188	* returns true with another value.
3189	* @ingroup mutating_algorithms
3190	* @param __first An input iterator.
3191	* @param __last An input iterator.
3192	* @param __result An output iterator.
3193	* @param __pred A predicate.
3194	* @param __new_value The replacement value.
3195	* @return The end of the output sequence, @p __result+(__last-__first).
3196	*
3197	* Copies each element in the range @p [__first,__last) to the range
3198	* @p [__result,__result+(__last-__first)) replacing elements for which
3199	* @p __pred returns true with @p __new_value.
3200	*/
3201	template<typename _InputIterator, typename _OutputIterator,
3202	typename _Predicate, typename _Tp>
3203	_GLIBCXX20_CONSTEXPR
3204	inline _OutputIterator
3205	replace_copy_if(_InputIterator __first, _InputIterator __last,
3206	_OutputIterator __result,
3207	_Predicate __pred, const _Tp& __new_value)
3208	{
3209	// concept requirements
3210	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
3211	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
3212	typename iterator_traits<_InputIterator>::value_type>)
3213	__glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
3214	typename iterator_traits<_InputIterator>::value_type>)
3215	__glibcxx_requires_valid_range(__first, __last);
3216
3217	return std::__replace_copy_if(__first, __last, __result,
3218	__gnu_cxx::__ops::__pred_iter(__pred),
3219	__new_value);
3220	}
3221
3222	#if __cplusplus >= 201103L
3223	/**
3224	* @brief Determines whether the elements of a sequence are sorted.
3225	* @ingroup sorting_algorithms
3226	* @param __first An iterator.
3227	* @param __last Another iterator.
3228	* @return True if the elements are sorted, false otherwise.
3229	*/
3230	template<typename _ForwardIterator>
3231	_GLIBCXX20_CONSTEXPR
3232	inline bool
3233	is_sorted(_ForwardIterator __first, _ForwardIterator __last)
3234	{ return std::is_sorted_until(__first, __last) == __last; }
3235
3236	/**
3237	* @brief Determines whether the elements of a sequence are sorted
3238	* according to a comparison functor.
3239	* @ingroup sorting_algorithms
3240	* @param __first An iterator.
3241	* @param __last Another iterator.
3242	* @param __comp A comparison functor.
3243	* @return True if the elements are sorted, false otherwise.
3244	*/
3245	template<typename _ForwardIterator, typename _Compare>
3246	_GLIBCXX20_CONSTEXPR
3247	inline bool
3248	is_sorted(_ForwardIterator __first, _ForwardIterator __last,
3249	_Compare __comp)
3250	{ return std::is_sorted_until(__first, __last, __comp) == __last; }
3251
3252	template<typename _ForwardIterator, typename _Compare>
3253	_GLIBCXX20_CONSTEXPR
3254	_ForwardIterator
3255	__is_sorted_until(_ForwardIterator __first, _ForwardIterator __last,
3256	_Compare __comp)
3257	{
3258	if (__first == __last)
3259	return __last;
3260
3261	_ForwardIterator __next = __first;
3262	for (++__next; __next != __last; __first = __next, (void)++__next)
3263	if (__comp(__next, __first))
3264	return __next;
3265	return __next;
3266	}
3267
3268	/**
3269	* @brief Determines the end of a sorted sequence.
3270	* @ingroup sorting_algorithms
3271	* @param __first An iterator.
3272	* @param __last Another iterator.
3273	* @return An iterator pointing to the last iterator i in [__first, __last)
3274	* for which the range [__first, i) is sorted.
3275	*/
3276	template<typename _ForwardIterator>
3277	_GLIBCXX20_CONSTEXPR
3278	inline _ForwardIterator
3279	is_sorted_until(_ForwardIterator __first, _ForwardIterator __last)
3280	{
3281	// concept requirements
3282	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
3283	__glibcxx_function_requires(_LessThanComparableConcept<
3284	typename iterator_traits<_ForwardIterator>::value_type>)
3285	__glibcxx_requires_valid_range(__first, __last);
3286	__glibcxx_requires_irreflexive(__first, __last);
3287
3288	return std::__is_sorted_until(__first, __last,
3289	__gnu_cxx::__ops::__iter_less_iter());
3290	}
3291
3292	/**
3293	* @brief Determines the end of a sorted sequence using comparison functor.
3294	* @ingroup sorting_algorithms
3295	* @param __first An iterator.
3296	* @param __last Another iterator.
3297	* @param __comp A comparison functor.
3298	* @return An iterator pointing to the last iterator i in [__first, __last)
3299	* for which the range [__first, i) is sorted.
3300	*/
3301	template<typename _ForwardIterator, typename _Compare>
3302	_GLIBCXX20_CONSTEXPR
3303	inline _ForwardIterator
3304	is_sorted_until(_ForwardIterator __first, _ForwardIterator __last,
3305	_Compare __comp)
3306	{
3307	// concept requirements
3308	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
3309	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
3310	typename iterator_traits<_ForwardIterator>::value_type,
3311	typename iterator_traits<_ForwardIterator>::value_type>)
3312	__glibcxx_requires_valid_range(__first, __last);
3313	__glibcxx_requires_irreflexive_pred(__first, __last, __comp);
3314
3315	return std::__is_sorted_until(__first, __last,
3316	__gnu_cxx::__ops::__iter_comp_iter(__comp));
3317	}
3318
3319	/**
3320	* @brief Determines min and max at once as an ordered pair.
3321	* @ingroup sorting_algorithms
3322	* @param __a A thing of arbitrary type.
3323	* @param __b Another thing of arbitrary type.
3324	* @return A pair(__b, __a) if __b is smaller than __a, pair(__a,
3325	* __b) otherwise.
3326	*/
3327	template<typename _Tp>
3328	_GLIBCXX14_CONSTEXPR
3329	inline pair<const _Tp&, const _Tp&>
3330	minmax(const _Tp& __a, const _Tp& __b)
3331	{
3332	// concept requirements
3333	__glibcxx_function_requires(_LessThanComparableConcept<_Tp>)
3334
3335	return __b < __a ? pair<const _Tp&, const _Tp&>(__b, __a)
3336	: pair<const _Tp&, const _Tp&>(__a, __b);
3337	}
3338
3339	/**
3340	* @brief Determines min and max at once as an ordered pair.
3341	* @ingroup sorting_algorithms
3342	* @param __a A thing of arbitrary type.
3343	* @param __b Another thing of arbitrary type.
3344	* @param __comp A @link comparison_functors comparison functor @endlink.
3345	* @return A pair(__b, __a) if __b is smaller than __a, pair(__a,
3346	* __b) otherwise.
3347	*/
3348	template<typename _Tp, typename _Compare>
3349	_GLIBCXX14_CONSTEXPR
3350	inline pair<const _Tp&, const _Tp&>
3351	minmax(const _Tp& __a, const _Tp& __b, _Compare __comp)
3352	{
3353	return __comp(__b, __a) ? pair<const _Tp&, const _Tp&>(__b, __a)
3354	: pair<const _Tp&, const _Tp&>(__a, __b);
3355	}
3356
3357	template<typename _ForwardIterator, typename _Compare>
3358	_GLIBCXX14_CONSTEXPR
3359	pair<_ForwardIterator, _ForwardIterator>
3360	__minmax_element(_ForwardIterator __first, _ForwardIterator __last,
3361	_Compare __comp)
3362	{
3363	_ForwardIterator __next = __first;
3364	if (__first == __last
3365	\|\| ++__next == __last)
3366	return std::make_pair(__first, __first);
3367
3368	_ForwardIterator __min{}, __max{};
3369	if (__comp(__next, __first))
3370	{
3371	__min = __next;
3372	__max = __first;
3373	}
3374	else
3375	{
3376	__min = __first;
3377	__max = __next;
3378	}
3379
3380	__first = __next;
3381	++__first;
3382
3383	while (__first != __last)
3384	{
3385	__next = __first;
3386	if (++__next == __last)
3387	{
3388	if (__comp(__first, __min))
3389	__min = __first;
3390	else if (!__comp(__first, __max))
3391	__max = __first;
3392	break;
3393	}
3394
3395	if (__comp(__next, __first))
3396	{
3397	if (__comp(__next, __min))
3398	__min = __next;
3399	if (!__comp(__first, __max))
3400	__max = __first;
3401	}
3402	else
3403	{
3404	if (__comp(__first, __min))
3405	__min = __first;
3406	if (!__comp(__next, __max))
3407	__max = __next;
3408	}
3409
3410	__first = __next;
3411	++__first;
3412	}
3413
3414	return std::make_pair(__min, __max);
3415	}
3416
3417	/**
3418	* @brief Return a pair of iterators pointing to the minimum and maximum
3419	* elements in a range.
3420	* @ingroup sorting_algorithms
3421	* @param __first Start of range.
3422	* @param __last End of range.
3423	* @return make_pair(m, M), where m is the first iterator i in
3424	* [__first, __last) such that no other element in the range is
3425	* smaller, and where M is the last iterator i in [__first, __last)
3426	* such that no other element in the range is larger.
3427	*/
3428	template<typename _ForwardIterator>
3429	_GLIBCXX14_CONSTEXPR
3430	inline pair<_ForwardIterator, _ForwardIterator>
3431	minmax_element(_ForwardIterator __first, _ForwardIterator __last)
3432	{
3433	// concept requirements
3434	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
3435	__glibcxx_function_requires(_LessThanComparableConcept<
3436	typename iterator_traits<_ForwardIterator>::value_type>)
3437	__glibcxx_requires_valid_range(__first, __last);
3438	__glibcxx_requires_irreflexive(__first, __last);
3439
3440	return std::__minmax_element(__first, __last,
3441	__gnu_cxx::__ops::__iter_less_iter());
3442	}
3443
3444	/**
3445	* @brief Return a pair of iterators pointing to the minimum and maximum
3446	* elements in a range.
3447	* @ingroup sorting_algorithms
3448	* @param __first Start of range.
3449	* @param __last End of range.
3450	* @param __comp Comparison functor.
3451	* @return make_pair(m, M), where m is the first iterator i in
3452	* [__first, __last) such that no other element in the range is
3453	* smaller, and where M is the last iterator i in [__first, __last)
3454	* such that no other element in the range is larger.
3455	*/
3456	template<typename _ForwardIterator, typename _Compare>
3457	_GLIBCXX14_CONSTEXPR
3458	inline pair<_ForwardIterator, _ForwardIterator>
3459	minmax_element(_ForwardIterator __first, _ForwardIterator __last,
3460	_Compare __comp)
3461	{
3462	// concept requirements
3463	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
3464	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
3465	typename iterator_traits<_ForwardIterator>::value_type,
3466	typename iterator_traits<_ForwardIterator>::value_type>)
3467	__glibcxx_requires_valid_range(__first, __last);
3468	__glibcxx_requires_irreflexive_pred(__first, __last, __comp);
3469
3470	return std::__minmax_element(__first, __last,
3471	__gnu_cxx::__ops::__iter_comp_iter(__comp));
3472	}
3473
3474	template<typename _Tp>
3475	_GLIBCXX14_CONSTEXPR
3476	inline pair<_Tp, _Tp>
3477	minmax(initializer_list<_Tp> __l)
3478	{
3479	__glibcxx_requires_irreflexive(__l.begin(), __l.end());
3480	pair<const _Tp, const* _Tp*> __p =
3481	std::__minmax_element(__l.begin(), __l.end(),
3482	__gnu_cxx::__ops::__iter_less_iter());
3483	return std::make_pair(__p.first, __p.second);
3484	}
3485
3486	template<typename _Tp, typename _Compare>
3487	_GLIBCXX14_CONSTEXPR
3488	inline pair<_Tp, _Tp>
3489	minmax(initializer_list<_Tp> __l, _Compare __comp)
3490	{
3491	__glibcxx_requires_irreflexive_pred(__l.begin(), __l.end(), __comp);
3492	pair<const _Tp, const* _Tp*> __p =
3493	std::__minmax_element(__l.begin(), __l.end(),
3494	__gnu_cxx::__ops::__iter_comp_iter(__comp));
3495	return std::make_pair(__p.first, __p.second);
3496	}
3497
3498	/**
3499	* @brief Checks whether a permutation of the second sequence is equal
3500	* to the first sequence.
3501	* @ingroup non_mutating_algorithms
3502	* @param __first1 Start of first range.
3503	* @param __last1 End of first range.
3504	* @param __first2 Start of second range.
3505	* @param __pred A binary predicate.
3506	* @return true if there exists a permutation of the elements in
3507	* the range [__first2, __first2 + (__last1 - __first1)),
3508	* beginning with ForwardIterator2 begin, such that
3509	* equal(__first1, __last1, __begin, __pred) returns true;
3510	* otherwise, returns false.
3511	*/
3512	template<typename _ForwardIterator1, typename _ForwardIterator2,
3513	typename _BinaryPredicate>
3514	_GLIBCXX20_CONSTEXPR
3515	inline bool
3516	is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
3517	_ForwardIterator2 __first2, _BinaryPredicate __pred)
3518	{
3519	// concept requirements
3520	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator1>)
3521	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator2>)
3522	__glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
3523	typename iterator_traits<_ForwardIterator1>::value_type,
3524	typename iterator_traits<_ForwardIterator2>::value_type>)
3525	__glibcxx_requires_valid_range(__first1, __last1);
3526
3527	return std::__is_permutation(__first1, __last1, __first2,
3528	__gnu_cxx::__ops::__iter_comp_iter(__pred));
3529	}
3530
3531	#if __cplusplus > 201103L
3532	template<typename _ForwardIterator1, typename _ForwardIterator2,
3533	typename _BinaryPredicate>
3534	_GLIBCXX20_CONSTEXPR
3535	bool
3536	__is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
3537	_ForwardIterator2 __first2, _ForwardIterator2 __last2,
3538	_BinaryPredicate __pred)
3539	{
3540	using _Cat1
3541	= typename iterator_traits<_ForwardIterator1>::iterator_category;
3542	using _Cat2
3543	= typename iterator_traits<_ForwardIterator2>::iterator_category;
3544	using _It1_is_RA = is_same<_Cat1, random_access_iterator_tag>;
3545	using _It2_is_RA = is_same<_Cat2, random_access_iterator_tag>;
3546	constexpr bool __ra_iters = _It1_is_RA() && _It2_is_RA();
3547	if (__ra_iters)
3548	{
3549	auto __d1 = std::distance(__first1, __last1);
3550	auto __d2 = std::distance(__first2, __last2);
3551	if (__d1 != __d2)
3552	return false;
3553	}
3554
3555	// Efficiently compare identical prefixes: O(N) if sequences
3556	// have the same elements in the same order.
3557	for (; __first1 != __last1 && __first2 != __last2;
3558	++__first1, (void)++__first2)
3559	if (!__pred(__first1, __first2))
3560	break;
3561
3562	if (__ra_iters)
3563	{
3564	if (__first1 == __last1)
3565	return true;
3566	}
3567	else
3568	{
3569	auto __d1 = std::distance(__first1, __last1);
3570	auto __d2 = std::distance(__first2, __last2);
3571	if (__d1 == `0` && __d2 == `0`)
3572	return true;
3573	if (__d1 != __d2)
3574	return false;
3575	}
3576
3577	for (_ForwardIterator1 __scan = __first1; __scan != __last1; ++__scan)
3578	{
3579	if (__scan != std::__find_if(__first1, __scan,
3580	__gnu_cxx::__ops::__iter_comp_iter(__pred, __scan)))
3581	continue; // We've seen this one before.
3582
3583	auto __matches = std::__count_if(__first2, __last2,
3584	__gnu_cxx::__ops::__iter_comp_iter(__pred, __scan));
3585	if (`0` == __matches
3586	\|\| std::__count_if(__scan, __last1,
3587	__gnu_cxx::__ops::__iter_comp_iter(__pred, __scan))
3588	!= __matches)
3589	return false;
3590	}
3591	return true;
3592	}
3593
3594	/**
3595	* @brief Checks whether a permutaion of the second sequence is equal
3596	* to the first sequence.
3597	* @ingroup non_mutating_algorithms
3598	* @param __first1 Start of first range.
3599	* @param __last1 End of first range.
3600	* @param __first2 Start of second range.
3601	* @param __last2 End of first range.
3602	* @return true if there exists a permutation of the elements in the range
3603	* [__first2, __last2), beginning with ForwardIterator2 begin,
3604	* such that equal(__first1, __last1, begin) returns true;
3605	* otherwise, returns false.
3606	*/
3607	template<typename _ForwardIterator1, typename _ForwardIterator2>
3608	_GLIBCXX20_CONSTEXPR
3609	inline bool
3610	is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
3611	_ForwardIterator2 __first2, _ForwardIterator2 __last2)
3612	{
3613	__glibcxx_requires_valid_range(__first1, __last1);
3614	__glibcxx_requires_valid_range(__first2, __last2);
3615
3616	return
3617	std::__is_permutation(__first1, __last1, __first2, __last2,
3618	__gnu_cxx::__ops::__iter_equal_to_iter());
3619	}
3620
3621	/**
3622	* @brief Checks whether a permutation of the second sequence is equal
3623	* to the first sequence.
3624	* @ingroup non_mutating_algorithms
3625	* @param __first1 Start of first range.
3626	* @param __last1 End of first range.
3627	* @param __first2 Start of second range.
3628	* @param __last2 End of first range.
3629	* @param __pred A binary predicate.
3630	* @return true if there exists a permutation of the elements in the range
3631	* [__first2, __last2), beginning with ForwardIterator2 begin,
3632	* such that equal(__first1, __last1, __begin, __pred) returns true;
3633	* otherwise, returns false.
3634	*/
3635	template<typename _ForwardIterator1, typename _ForwardIterator2,
3636	typename _BinaryPredicate>
3637	_GLIBCXX20_CONSTEXPR
3638	inline bool
3639	is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
3640	_ForwardIterator2 __first2, _ForwardIterator2 __last2,
3641	_BinaryPredicate __pred)
3642	{
3643	__glibcxx_requires_valid_range(__first1, __last1);
3644	__glibcxx_requires_valid_range(__first2, __last2);
3645
3646	return std::__is_permutation(__first1, __last1, __first2, __last2,
3647	__gnu_cxx::__ops::__iter_comp_iter(__pred));
3648	}
3649
3650	#if __cplusplus >= 201703L
3651
3652	#define __cpp_lib_clamp 201603L
3653
3654	/**
3655	* @brief Returns the value clamped between lo and hi.
3656	* @ingroup sorting_algorithms
3657	* @param __val A value of arbitrary type.
3658	* @param __lo A lower limit of arbitrary type.
3659	* @param __hi An upper limit of arbitrary type.
3660	* @retval `__lo` if `__val < __lo`
3661	* @retval `__hi` if `__hi < __val`
3662	* @retval `__val` otherwise.
3663	* @pre `_Tp` is LessThanComparable and `(__hi < __lo)` is false.
3664	*/
3665	template<typename _Tp>
3666	constexpr const _Tp&
3667	clamp(const _Tp& __val, const _Tp& __lo, const _Tp& __hi)
3668	{
3669	__glibcxx_assert(!(__hi < __lo));
3670	return std::min(std::max(__val, __lo), __hi);
3671	}
3672
3673	/**
3674	* @brief Returns the value clamped between lo and hi.
3675	* @ingroup sorting_algorithms
3676	* @param __val A value of arbitrary type.
3677	* @param __lo A lower limit of arbitrary type.
3678	* @param __hi An upper limit of arbitrary type.
3679	* @param __comp A comparison functor.
3680	* @retval `__lo` if `__comp(__val, __lo)`
3681	* @retval `__hi` if `__comp(__hi, __val)`
3682	* @retval `__val` otherwise.
3683	* @pre `__comp(__hi, __lo)` is false.
3684	*/
3685	template<typename _Tp, typename _Compare>
3686	constexpr const _Tp&
3687	clamp(const _Tp& __val, const _Tp& __lo, const _Tp& __hi, _Compare __comp)
3688	{
3689	__glibcxx_assert(!__comp(__hi, __lo));
3690	return std::min(std::max(__val, __lo, __comp), __hi, __comp);
3691	}
3692	#endif // C++17
3693	#endif // C++14
3694
3695	#ifdef _GLIBCXX_USE_C99_STDINT_TR1
3696	/**
3697	* @brief Generate two uniformly distributed integers using a
3698	* single distribution invocation.
3699	* @param __b0 The upper bound for the first integer.
3700	* @param __b1 The upper bound for the second integer.
3701	* @param __g A UniformRandomBitGenerator.
3702	* @return A pair (i, j) with i and j uniformly distributed
3703	* over [0, __b0) and [0, __b1), respectively.
3704	*
3705	* Requires: __b0 * __b1 <= __g.max() - __g.min().
3706	*
3707	* Using uniform_int_distribution with a range that is very
3708	* small relative to the range of the generator ends up wasting
3709	* potentially expensively generated randomness, since
3710	* uniform_int_distribution does not store leftover randomness
3711	* between invocations.
3712	*
3713	* If we know we want two integers in ranges that are sufficiently
3714	* small, we can compose the ranges, use a single distribution
3715	* invocation, and significantly reduce the waste.
3716	*/
3717	template<typename _IntType, typename _UniformRandomBitGenerator>
3718	pair<_IntType, _IntType>
3719	__gen_two_uniform_ints(_IntType __b0, _IntType __b1,
3720	_UniformRandomBitGenerator&& __g)
3721	{
3722	_IntType __x
3723	= uniform_int_distribution<_IntType>{`0`, (__b0 * __b1) - `1`}(__g);
3724	return std::make_pair(__x / __b1, __x % __b1);
3725	}
3726
3727	/**
3728	* @brief Shuffle the elements of a sequence using a uniform random
3729	* number generator.
3730	* @ingroup mutating_algorithms
3731	* @param __first A forward iterator.
3732	* @param __last A forward iterator.
3733	* @param __g A UniformRandomNumberGenerator (26.5.1.3).
3734	* @return Nothing.
3735	*
3736	* Reorders the elements in the range @p [__first,__last) using @p __g to
3737	* provide random numbers.
3738	*/
3739	template<typename _RandomAccessIterator,
3740	typename _UniformRandomNumberGenerator>
3741	void
3742	shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last,
3743	_UniformRandomNumberGenerator&& __g)
3744	{
3745	// concept requirements
3746	__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
3747	_RandomAccessIterator>)
3748	__glibcxx_requires_valid_range(__first, __last);
3749
3750	if (__first == __last)
3751	return;
3752
3753	typedef typename iterator_traits<_RandomAccessIterator>::difference_type
3754	_DistanceType;
3755
3756	typedef typename std::make_unsigned<_DistanceType>::type __ud_type;
3757	typedef typename std::uniform_int_distribution<__ud_type> __distr_type;
3758	typedef typename __distr_type::param_type __p_type;
3759
3760	typedef typename remove_reference<_UniformRandomNumberGenerator>::type
3761	_Gen;
3762	typedef typename common_type<typename _Gen::result_type, __ud_type>::type
3763	__uc_type;
3764
3765	const __uc_type __urngrange = __g.max() - __g.min();
3766	const __uc_type __urange = __uc_type(__last - __first);
3767
3768	if (__urngrange / __urange >= __urange)
3769	// I.e. (__urngrange >= __urange __urange) but without wrap issues.*
3770	{
3771	_RandomAccessIterator __i = __first + `1`;
3772
3773	// Since we know the range isn't empty, an even number of elements
3774	// means an uneven number of elements /to swap/, in which case we
3775	// do the first one up front:
3776
3777	if ((__urange % `2`) == `0`)
3778	{
3779	__distr_type __d{`0`, `1`};
3780	std::iter_swap(__i++, __first + __d(__g));
3781	}
3782
3783	// Now we know that __last - __i is even, so we do the rest in pairs,
3784	// using a single distribution invocation to produce swap positions
3785	// for two successive elements at a time:
3786
3787	while (__i != __last)
3788	{
3789	const __uc_type __swap_range = __uc_type(__i - __first) + `1`;
3790
3791	const pair<__uc_type, __uc_type> __pospos =
3792	__gen_two_uniform_ints(__swap_range, __swap_range + `1`, __g);
3793
3794	std::iter_swap(__i++, __first + __pospos.first);
3795	std::iter_swap(__i++, __first + __pospos.second);
3796	}
3797
3798	return;
3799	}
3800
3801	__distr_type __d;
3802
3803	for (_RandomAccessIterator __i = __first + `1`; __i != __last; ++__i)
3804	std::iter_swap(__i, __first + __d(__g, __p_type(`0`, __i - __first)));
3805	}
3806	#endif // USE C99_STDINT
3807
3808	#endif // C++11
3809
3810	_GLIBCXX_BEGIN_NAMESPACE_ALGO
3811
3812	/**
3813	* @brief Apply a function to every element of a sequence.
3814	* @ingroup non_mutating_algorithms
3815	* @param __first An input iterator.
3816	* @param __last An input iterator.
3817	* @param __f A unary function object.
3818	* @return @p __f
3819	*
3820	* Applies the function object @p __f to each element in the range
3821	* @p [first,last). @p __f must not modify the order of the sequence.
3822	* If @p __f has a return value it is ignored.
3823	*/
3824	template<typename _InputIterator, typename _Function>
3825	_GLIBCXX20_CONSTEXPR
3826	_Function
3827	for_each(_InputIterator __first, _InputIterator __last, _Function __f)
3828	{
3829	// concept requirements
3830	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
3831	__glibcxx_requires_valid_range(__first, __last);
3832	for (; __first != __last; ++__first)
3833	__f(*__first);
3834	return __f; // N.B. [alg.foreach] says std::move(f) but it's redundant.
3835	}
3836
3837	#if __cplusplus >= 201703L
3838	/**
3839	* @brief Apply a function to every element of a sequence.
3840	* @ingroup non_mutating_algorithms
3841	* @param __first An input iterator.
3842	* @param __n A value convertible to an integer.
3843	* @param __f A unary function object.
3844	* @return `__first+__n`
3845	*
3846	* Applies the function object `__f` to each element in the range
3847	* `[first, first+n)`. `__f` must not modify the order of the sequence.
3848	* If `__f` has a return value it is ignored.
3849	*/
3850	template<typename _InputIterator, typename _Size, typename _Function>
3851	_GLIBCXX20_CONSTEXPR
3852	_InputIterator
3853	for_each_n(_InputIterator __first, _Size __n, _Function __f)
3854	{
3855	auto __n2 = std::__size_to_integer(__n);
3856	using _Cat = typename iterator_traits<_InputIterator>::iterator_category;
3857	if constexpr (is_base_of_v<random_access_iterator_tag, _Cat>)
3858	{
3859	if (__n2 <= `0`)
3860	return __first;
3861	auto __last = __first + __n2;
3862	std::for_each(__first, __last, std::move(__f));
3863	return __last;
3864	}
3865	else
3866	{
3867	while (__n2-->`0`)
3868	{
3869	__f(*__first);
3870	++__first;
3871	}
3872	return __first;
3873	}
3874	}
3875	#endif // C++17
3876
3877	/**
3878	* @brief Find the first occurrence of a value in a sequence.
3879	* @ingroup non_mutating_algorithms
3880	* @param __first An input iterator.
3881	* @param __last An input iterator.
3882	* @param __val The value to find.
3883	* @return The first iterator @c i in the range @p [__first,__last)
3884	* such that @c *i == @p __val, or @p __last if no such iterator exists.
3885	*/
3886	template<typename _InputIterator, typename _Tp>
3887	_GLIBCXX20_CONSTEXPR
3888	inline _InputIterator
3889	find(_InputIterator __first, _InputIterator __last,
3890	const _Tp& __val)
3891	{
3892	// concept requirements
3893	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
3894	__glibcxx_function_requires(_EqualOpConcept<
3895	typename iterator_traits<_InputIterator>::value_type, _Tp>)
3896	__glibcxx_requires_valid_range(__first, __last);
3897	return std::__find_if(__first, __last,
3898	__gnu_cxx::__ops::__iter_equals_val(__val));
3899	}
3900
3901	/**
3902	* @brief Find the first element in a sequence for which a
3903	* predicate is true.
3904	* @ingroup non_mutating_algorithms
3905	* @param __first An input iterator.
3906	* @param __last An input iterator.
3907	* @param __pred A predicate.
3908	* @return The first iterator @c i in the range @p [__first,__last)
3909	* such that @p __pred(*i) is true, or @p __last if no such iterator exists.
3910	*/
3911	template<typename _InputIterator, typename _Predicate>
3912	_GLIBCXX20_CONSTEXPR
3913	inline _InputIterator
3914	find_if(_InputIterator __first, _InputIterator __last,
3915	_Predicate __pred)
3916	{
3917	// concept requirements
3918	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
3919	__glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
3920	typename iterator_traits<_InputIterator>::value_type>)
3921	__glibcxx_requires_valid_range(__first, __last);
3922
3923	return std::__find_if(__first, __last,
3924	__gnu_cxx::__ops::__pred_iter(__pred));
3925	}
3926
3927	/**
3928	* @brief Find element from a set in a sequence.
3929	* @ingroup non_mutating_algorithms
3930	* @param __first1 Start of range to search.
3931	* @param __last1 End of range to search.
3932	* @param __first2 Start of match candidates.
3933	* @param __last2 End of match candidates.
3934	* @return The first iterator @c i in the range
3935	* @p [__first1,__last1) such that @c i == @p (i2) such that i2 is an
3936	* iterator in [__first2,__last2), or @p __last1 if no such iterator exists.
3937	*
3938	* Searches the range @p [__first1,__last1) for an element that is
3939	* equal to some element in the range [__first2,__last2). If
3940	* found, returns an iterator in the range [__first1,__last1),
3941	* otherwise returns @p __last1.
3942	*/
3943	template<typename _InputIterator, typename _ForwardIterator>
3944	_GLIBCXX20_CONSTEXPR
3945	_InputIterator
3946	find_first_of(_InputIterator __first1, _InputIterator __last1,
3947	_ForwardIterator __first2, _ForwardIterator __last2)
3948	{
3949	// concept requirements
3950	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
3951	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
3952	__glibcxx_function_requires(_EqualOpConcept<
3953	typename iterator_traits<_InputIterator>::value_type,
3954	typename iterator_traits<_ForwardIterator>::value_type>)
3955	__glibcxx_requires_valid_range(__first1, __last1);
3956	__glibcxx_requires_valid_range(__first2, __last2);
3957
3958	for (; __first1 != __last1; ++__first1)
3959	for (_ForwardIterator __iter = __first2; __iter != __last2; ++__iter)
3960	if (__first1 == __iter)
3961	return __first1;
3962	return __last1;
3963	}
3964
3965	/**
3966	* @brief Find element from a set in a sequence using a predicate.
3967	* @ingroup non_mutating_algorithms
3968	* @param __first1 Start of range to search.
3969	* @param __last1 End of range to search.
3970	* @param __first2 Start of match candidates.
3971	* @param __last2 End of match candidates.
3972	* @param __comp Predicate to use.
3973	* @return The first iterator @c i in the range
3974	* @p [__first1,__last1) such that @c comp(i, @p (i2)) is true
3975	* and i2 is an iterator in [__first2,__last2), or @p __last1 if no
3976	* such iterator exists.
3977	*
3978
3979	* Searches the range @p [__first1,__last1) for an element that is
3980	* equal to some element in the range [__first2,__last2). If
3981	* found, returns an iterator in the range [__first1,__last1),
3982	* otherwise returns @p __last1.
3983	*/
3984	template<typename _InputIterator, typename _ForwardIterator,
3985	typename _BinaryPredicate>
3986	_GLIBCXX20_CONSTEXPR
3987	_InputIterator
3988	find_first_of(_InputIterator __first1, _InputIterator __last1,
3989	_ForwardIterator __first2, _ForwardIterator __last2,
3990	_BinaryPredicate __comp)
3991	{
3992	// concept requirements
3993	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
3994	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
3995	__glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
3996	typename iterator_traits<_InputIterator>::value_type,
3997	typename iterator_traits<_ForwardIterator>::value_type>)
3998	__glibcxx_requires_valid_range(__first1, __last1);
3999	__glibcxx_requires_valid_range(__first2, __last2);
4000
4001	for (; __first1 != __last1; ++__first1)
4002	for (_ForwardIterator __iter = __first2; __iter != __last2; ++__iter)
4003	if (__comp(__first1, __iter))
4004	return __first1;
4005	return __last1;
4006	}
4007
4008	/**
4009	* @brief Find two adjacent values in a sequence that are equal.
4010	* @ingroup non_mutating_algorithms
4011	* @param __first A forward iterator.
4012	* @param __last A forward iterator.
4013	* @return The first iterator @c i such that @c i and @c i+1 are both
4014	* valid iterators in @p [__first,__last) and such that @c i == @c (i+1),
4015	* or @p __last if no such iterator exists.
4016	*/
4017	template<typename _ForwardIterator>
4018	_GLIBCXX20_CONSTEXPR
4019	inline _ForwardIterator
4020	adjacent_find(_ForwardIterator __first, _ForwardIterator __last)
4021	{
4022	// concept requirements
4023	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
4024	__glibcxx_function_requires(_EqualityComparableConcept<
4025	typename iterator_traits<_ForwardIterator>::value_type>)
4026	__glibcxx_requires_valid_range(__first, __last);
4027
4028	return std::__adjacent_find(__first, __last,
4029	__gnu_cxx::__ops::__iter_equal_to_iter());
4030	}
4031
4032	/**
4033	* @brief Find two adjacent values in a sequence using a predicate.
4034	* @ingroup non_mutating_algorithms
4035	* @param __first A forward iterator.
4036	* @param __last A forward iterator.
4037	* @param __binary_pred A binary predicate.
4038	* @return The first iterator @c i such that @c i and @c i+1 are both
4039	* valid iterators in @p [__first,__last) and such that
4040	* @p __binary_pred(i,(i+1)) is true, or @p __last if no such iterator
4041	* exists.
4042	*/
4043	template<typename _ForwardIterator, typename _BinaryPredicate>
4044	_GLIBCXX20_CONSTEXPR
4045	inline _ForwardIterator
4046	adjacent_find(_ForwardIterator __first, _ForwardIterator __last,
4047	_BinaryPredicate __binary_pred)
4048	{
4049	// concept requirements
4050	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
4051	__glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
4052	typename iterator_traits<_ForwardIterator>::value_type,
4053	typename iterator_traits<_ForwardIterator>::value_type>)
4054	__glibcxx_requires_valid_range(__first, __last);
4055
4056	return std::__adjacent_find(__first, __last,
4057	__gnu_cxx::__ops::__iter_comp_iter(__binary_pred));
4058	}
4059
4060	/**
4061	* @brief Count the number of copies of a value in a sequence.
4062	* @ingroup non_mutating_algorithms
4063	* @param __first An input iterator.
4064	* @param __last An input iterator.
4065	* @param __value The value to be counted.
4066	* @return The number of iterators @c i in the range @p [__first,__last)
4067	* for which @c *i == @p __value
4068	*/
4069	template<typename _InputIterator, typename _Tp>
4070	_GLIBCXX20_CONSTEXPR
4071	inline typename iterator_traits<_InputIterator>::difference_type
4072	count(_InputIterator __first, _InputIterator __last, const _Tp& __value)
4073	{
4074	// concept requirements
4075	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
4076	__glibcxx_function_requires(_EqualOpConcept<
4077	typename iterator_traits<_InputIterator>::value_type, _Tp>)
4078	__glibcxx_requires_valid_range(__first, __last);
4079
4080	return std::__count_if(__first, __last,
4081	__gnu_cxx::__ops::__iter_equals_val(__value));
4082	}
4083
4084	/**
4085	* @brief Count the elements of a sequence for which a predicate is true.
4086	* @ingroup non_mutating_algorithms
4087	* @param __first An input iterator.
4088	* @param __last An input iterator.
4089	* @param __pred A predicate.
4090	* @return The number of iterators @c i in the range @p [__first,__last)
4091	* for which @p __pred(*i) is true.
4092	*/
4093	template<typename _InputIterator, typename _Predicate>
4094	_GLIBCXX20_CONSTEXPR
4095	inline typename iterator_traits<_InputIterator>::difference_type
4096	count_if(_InputIterator __first, _InputIterator __last, _Predicate __pred)
4097	{
4098	// concept requirements
4099	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
4100	__glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
4101	typename iterator_traits<_InputIterator>::value_type>)
4102	__glibcxx_requires_valid_range(__first, __last);
4103
4104	return std::__count_if(__first, __last,
4105	__gnu_cxx::__ops::__pred_iter(__pred));
4106	}
4107
4108	/**
4109	* @brief Search a sequence for a matching sub-sequence.
4110	* @ingroup non_mutating_algorithms
4111	* @param __first1 A forward iterator.
4112	* @param __last1 A forward iterator.
4113	* @param __first2 A forward iterator.
4114	* @param __last2 A forward iterator.
4115	* @return The first iterator @c i in the range @p
4116	* [__first1,__last1-(__last2-__first2)) such that @c *(i+N) == @p
4117	* *(__first2+N) for each @c N in the range @p
4118	* [0,__last2-__first2), or @p __last1 if no such iterator exists.
4119	*
4120	* Searches the range @p [__first1,__last1) for a sub-sequence that
4121	* compares equal value-by-value with the sequence given by @p
4122	* [__first2,__last2) and returns an iterator to the first element
4123	* of the sub-sequence, or @p __last1 if the sub-sequence is not
4124	* found.
4125	*
4126	* Because the sub-sequence must lie completely within the range @p
4127	* [__first1,__last1) it must start at a position less than @p
4128	* __last1-(__last2-__first2) where @p __last2-__first2 is the
4129	* length of the sub-sequence.
4130	*
4131	* This means that the returned iterator @c i will be in the range
4132	* @p [__first1,__last1-(__last2-__first2))
4133	*/
4134	template<typename _ForwardIterator1, typename _ForwardIterator2>
4135	_GLIBCXX20_CONSTEXPR
4136	inline _ForwardIterator1
4137	search(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
4138	_ForwardIterator2 __first2, _ForwardIterator2 __last2)
4139	{
4140	// concept requirements
4141	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator1>)
4142	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator2>)
4143	__glibcxx_function_requires(_EqualOpConcept<
4144	typename iterator_traits<_ForwardIterator1>::value_type,
4145	typename iterator_traits<_ForwardIterator2>::value_type>)
4146	__glibcxx_requires_valid_range(__first1, __last1);
4147	__glibcxx_requires_valid_range(__first2, __last2);
4148
4149	return std::__search(__first1, __last1, __first2, __last2,
4150	__gnu_cxx::__ops::__iter_equal_to_iter());
4151	}
4152
4153	/**
4154	* @brief Search a sequence for a matching sub-sequence using a predicate.
4155	* @ingroup non_mutating_algorithms
4156	* @param __first1 A forward iterator.
4157	* @param __last1 A forward iterator.
4158	* @param __first2 A forward iterator.
4159	* @param __last2 A forward iterator.
4160	* @param __predicate A binary predicate.
4161	* @return The first iterator @c i in the range
4162	* @p [__first1,__last1-(__last2-__first2)) such that
4163	* @p __predicate((i+N),(__first2+N)) is true for each @c N in the range
4164	* @p [0,__last2-__first2), or @p __last1 if no such iterator exists.
4165	*
4166	* Searches the range @p [__first1,__last1) for a sub-sequence that
4167	* compares equal value-by-value with the sequence given by @p
4168	* [__first2,__last2), using @p __predicate to determine equality,
4169	* and returns an iterator to the first element of the
4170	* sub-sequence, or @p __last1 if no such iterator exists.
4171	*
4172	* @see search(_ForwardIter1, _ForwardIter1, _ForwardIter2, _ForwardIter2)
4173	*/
4174	template<typename _ForwardIterator1, typename _ForwardIterator2,
4175	typename _BinaryPredicate>
4176	_GLIBCXX20_CONSTEXPR
4177	inline _ForwardIterator1
4178	search(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
4179	_ForwardIterator2 __first2, _ForwardIterator2 __last2,
4180	_BinaryPredicate __predicate)
4181	{
4182	// concept requirements
4183	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator1>)
4184	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator2>)
4185	__glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
4186	typename iterator_traits<_ForwardIterator1>::value_type,
4187	typename iterator_traits<_ForwardIterator2>::value_type>)
4188	__glibcxx_requires_valid_range(__first1, __last1);
4189	__glibcxx_requires_valid_range(__first2, __last2);
4190
4191	return std::__search(__first1, __last1, __first2, __last2,
4192	__gnu_cxx::__ops::__iter_comp_iter(__predicate));
4193	}
4194
4195	/**
4196	* @brief Search a sequence for a number of consecutive values.
4197	* @ingroup non_mutating_algorithms
4198	* @param __first A forward iterator.
4199	* @param __last A forward iterator.
4200	* @param __count The number of consecutive values.
4201	* @param __val The value to find.
4202	* @return The first iterator @c i in the range @p
4203	* [__first,__last-__count) such that @c *(i+N) == @p __val for
4204	* each @c N in the range @p [0,__count), or @p __last if no such
4205	* iterator exists.
4206	*
4207	* Searches the range @p [__first,__last) for @p count consecutive elements
4208	* equal to @p __val.
4209	*/
4210	template<typename _ForwardIterator, typename _Integer, typename _Tp>
4211	_GLIBCXX20_CONSTEXPR
4212	inline _ForwardIterator
4213	search_n(_ForwardIterator __first, _ForwardIterator __last,
4214	_Integer __count, const _Tp& __val)
4215	{
4216	// concept requirements
4217	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
4218	__glibcxx_function_requires(_EqualOpConcept<
4219	typename iterator_traits<_ForwardIterator>::value_type, _Tp>)
4220	__glibcxx_requires_valid_range(__first, __last);
4221
4222	return std::__search_n(__first, __last, __count,
4223	__gnu_cxx::__ops::__iter_equals_val(__val));
4224	}
4225
4226
4227	/**
4228	* @brief Search a sequence for a number of consecutive values using a
4229	* predicate.
4230	* @ingroup non_mutating_algorithms
4231	* @param __first A forward iterator.
4232	* @param __last A forward iterator.
4233	* @param __count The number of consecutive values.
4234	* @param __val The value to find.
4235	* @param __binary_pred A binary predicate.
4236	* @return The first iterator @c i in the range @p
4237	* [__first,__last-__count) such that @p
4238	* __binary_pred(*(i+N),__val) is true for each @c N in the range
4239	* @p [0,__count), or @p __last if no such iterator exists.
4240	*
4241	* Searches the range @p [__first,__last) for @p __count
4242	* consecutive elements for which the predicate returns true.
4243	*/
4244	template<typename _ForwardIterator, typename _Integer, typename _Tp,
4245	typename _BinaryPredicate>
4246	_GLIBCXX20_CONSTEXPR
4247	inline _ForwardIterator
4248	search_n(_ForwardIterator __first, _ForwardIterator __last,
4249	_Integer __count, const _Tp& __val,
4250	_BinaryPredicate __binary_pred)
4251	{
4252	// concept requirements
4253	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
4254	__glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
4255	typename iterator_traits<_ForwardIterator>::value_type, _Tp>)
4256	__glibcxx_requires_valid_range(__first, __last);
4257
4258	return std::__search_n(__first, __last, __count,
4259	__gnu_cxx::__ops::__iter_comp_val(__binary_pred, __val));
4260	}
4261
4262	#if __cplusplus >= 201703L
4263	/* @brief Search a sequence using a Searcher object.*
4264	*
4265	* @param __first A forward iterator.
4266	* @param __last A forward iterator.
4267	* @param __searcher A callable object.
4268	* @return @p __searcher(__first,__last).first
4269	*/
4270	template<typename _ForwardIterator, typename _Searcher>
4271	_GLIBCXX20_CONSTEXPR
4272	inline _ForwardIterator
4273	search(_ForwardIterator __first, _ForwardIterator __last,
4274	const _Searcher& __searcher)
4275	{ return __searcher(__first, __last).first; }
4276	#endif
4277
4278	/**
4279	* @brief Perform an operation on a sequence.
4280	* @ingroup mutating_algorithms
4281	* @param __first An input iterator.
4282	* @param __last An input iterator.
4283	* @param __result An output iterator.
4284	* @param __unary_op A unary operator.
4285	* @return An output iterator equal to @p __result+(__last-__first).
4286	*
4287	* Applies the operator to each element in the input range and assigns
4288	* the results to successive elements of the output sequence.
4289	* Evaluates @p (__result+N)=unary_op((__first+N)) for each @c N in the
4290	* range @p [0,__last-__first).
4291	*
4292	* @p unary_op must not alter its argument.
4293	*/
4294	template<typename _InputIterator, typename _OutputIterator,
4295	typename _UnaryOperation>
4296	_GLIBCXX20_CONSTEXPR
4297	_OutputIterator
4298	transform(_InputIterator __first, _InputIterator __last,
4299	_OutputIterator __result, _UnaryOperation __unary_op)
4300	{
4301	// concept requirements
4302	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
4303	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
4304	// "the type returned by a _UnaryOperation"
4305	__typeof__(__unary_op(*__first))>)
4306	__glibcxx_requires_valid_range(__first, __last);
4307
4308	for (; __first != __last; ++__first, (void)++__result)
4309	__result = __unary_op(__first);
4310	return __result;
4311	}
4312
4313	/**
4314	* @brief Perform an operation on corresponding elements of two sequences.
4315	* @ingroup mutating_algorithms
4316	* @param __first1 An input iterator.
4317	* @param __last1 An input iterator.
4318	* @param __first2 An input iterator.
4319	* @param __result An output iterator.
4320	* @param __binary_op A binary operator.
4321	* @return An output iterator equal to @p result+(last-first).
4322	*
4323	* Applies the operator to the corresponding elements in the two
4324	* input ranges and assigns the results to successive elements of the
4325	* output sequence.
4326	* Evaluates @p
4327	* (__result+N)=__binary_op((__first1+N),*(__first2+N)) for each
4328	* @c N in the range @p [0,__last1-__first1).
4329	*
4330	* @p binary_op must not alter either of its arguments.
4331	*/
4332	template<typename _InputIterator1, typename _InputIterator2,
4333	typename _OutputIterator, typename _BinaryOperation>
4334	_GLIBCXX20_CONSTEXPR
4335	_OutputIterator
4336	transform(_InputIterator1 __first1, _InputIterator1 __last1,
4337	_InputIterator2 __first2, _OutputIterator __result,
4338	_BinaryOperation __binary_op)
4339	{
4340	// concept requirements
4341	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
4342	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
4343	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
4344	// "the type returned by a _BinaryOperation"
4345	__typeof__(__binary_op(__first1,__first2))>)
4346	__glibcxx_requires_valid_range(__first1, __last1);
4347
4348	for (; __first1 != __last1; ++__first1, (void)++__first2, ++__result)
4349	__result = __binary_op(__first1, *__first2);
4350	return __result;
4351	}
4352
4353	/**
4354	* @brief Replace each occurrence of one value in a sequence with another
4355	* value.
4356	* @ingroup mutating_algorithms
4357	* @param __first A forward iterator.
4358	* @param __last A forward iterator.
4359	* @param __old_value The value to be replaced.
4360	* @param __new_value The replacement value.
4361	* @return replace() returns no value.
4362	*
4363	* For each iterator `i` in the range `[__first,__last)` if
4364	* `i == __old_value` then the assignment `i = __new_value` is performed.
4365	*/
4366	template<typename _ForwardIterator, typename _Tp>
4367	_GLIBCXX20_CONSTEXPR
4368	void
4369	replace(_ForwardIterator __first, _ForwardIterator __last,
4370	const _Tp& __old_value, const _Tp& __new_value)
4371	{
4372	// concept requirements
4373	__glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
4374	_ForwardIterator>)
4375	__glibcxx_function_requires(_EqualOpConcept<
4376	typename iterator_traits<_ForwardIterator>::value_type, _Tp>)
4377	__glibcxx_function_requires(_ConvertibleConcept<_Tp,
4378	typename iterator_traits<_ForwardIterator>::value_type>)
4379	__glibcxx_requires_valid_range(__first, __last);
4380
4381	for (; __first != __last; ++__first)
4382	if (*__first == __old_value)
4383	*__first = __new_value;
4384	}
4385
4386	/**
4387	* @brief Replace each value in a sequence for which a predicate returns
4388	* true with another value.
4389	* @ingroup mutating_algorithms
4390	* @param __first A forward iterator.
4391	* @param __last A forward iterator.
4392	* @param __pred A predicate.
4393	* @param __new_value The replacement value.
4394	* @return replace_if() returns no value.
4395	*
4396	* For each iterator `i` in the range `[__first,__last)` if `__pred(*i)`
4397	* is true then the assignment `*i = __new_value` is performed.
4398	*/
4399	template<typename _ForwardIterator, typename _Predicate, typename _Tp>
4400	_GLIBCXX20_CONSTEXPR
4401	void
4402	replace_if(_ForwardIterator __first, _ForwardIterator __last,
4403	_Predicate __pred, const _Tp& __new_value)
4404	{
4405	// concept requirements
4406	__glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
4407	_ForwardIterator>)
4408	__glibcxx_function_requires(_ConvertibleConcept<_Tp,
4409	typename iterator_traits<_ForwardIterator>::value_type>)
4410	__glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
4411	typename iterator_traits<_ForwardIterator>::value_type>)
4412	__glibcxx_requires_valid_range(__first, __last);
4413
4414	for (; __first != __last; ++__first)
4415	if (__pred(*__first))
4416	*__first = __new_value;
4417	}
4418
4419	/**
4420	* @brief Assign the result of a function object to each value in a
4421	* sequence.
4422	* @ingroup mutating_algorithms
4423	* @param __first A forward iterator.
4424	* @param __last A forward iterator.
4425	* @param __gen A function object callable with no arguments.
4426	* @return generate() returns no value.
4427	*
4428	* Performs the assignment `*i = __gen()` for each `i` in the range
4429	* `[__first, __last)`.
4430	*/
4431	template<typename _ForwardIterator, typename _Generator>
4432	_GLIBCXX20_CONSTEXPR
4433	void
4434	generate(_ForwardIterator __first, _ForwardIterator __last,
4435	_Generator __gen)
4436	{
4437	// concept requirements
4438	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
4439	__glibcxx_function_requires(_GeneratorConcept<_Generator,
4440	typename iterator_traits<_ForwardIterator>::value_type>)
4441	__glibcxx_requires_valid_range(__first, __last);
4442
4443	for (; __first != __last; ++__first)
4444	*__first = __gen();
4445	}
4446
4447	/**
4448	* @brief Assign the result of a function object to each value in a
4449	* sequence.
4450	* @ingroup mutating_algorithms
4451	* @param __first A forward iterator.
4452	* @param __n The length of the sequence.
4453	* @param __gen A function object callable with no arguments.
4454	* @return The end of the sequence, i.e., `__first + __n`
4455	*
4456	* Performs the assignment `*i = __gen()` for each `i` in the range
4457	* `[__first, __first + __n)`.
4458	*
4459	* If `__n` is negative, the function does nothing and returns `__first`.
4460	*/
4461	// _GLIBCXX_RESOLVE_LIB_DEFECTS
4462	// DR 865. More algorithms that throw away information
4463	// DR 426. search_n(), fill_n(), and generate_n() with negative n
4464	template<typename _OutputIterator, typename _Size, typename _Generator>
4465	_GLIBCXX20_CONSTEXPR
4466	_OutputIterator
4467	generate_n(_OutputIterator __first, _Size __n, _Generator __gen)
4468	{
4469	// concept requirements
4470	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
4471	// "the type returned by a _Generator"
4472	__typeof__(__gen())>)
4473
4474	typedef __decltype(std::__size_to_integer(__n)) _IntSize;
4475	for (_IntSize __niter = std::__size_to_integer(__n);
4476	__niter > `0`; --__niter, (void) ++__first)
4477	*__first = __gen();
4478	return __first;
4479	}
4480
4481	/**
4482	* @brief Copy a sequence, removing consecutive duplicate values.
4483	* @ingroup mutating_algorithms
4484	* @param __first An input iterator.
4485	* @param __last An input iterator.
4486	* @param __result An output iterator.
4487	* @return An iterator designating the end of the resulting sequence.
4488	*
4489	* Copies each element in the range `[__first, __last)` to the range
4490	* beginning at `__result`, except that only the first element is copied
4491	* from groups of consecutive elements that compare equal.
4492	* `unique_copy()` is stable, so the relative order of elements that are
4493	* copied is unchanged.
4494	*/
4495	// _GLIBCXX_RESOLVE_LIB_DEFECTS
4496	// DR 241. Does unique_copy() require CopyConstructible and Assignable?
4497	// DR 538. 241 again: Does unique_copy() require CopyConstructible and
4498	// Assignable?
4499	template<typename _InputIterator, typename _OutputIterator>
4500	_GLIBCXX20_CONSTEXPR
4501	inline _OutputIterator
4502	unique_copy(_InputIterator __first, _InputIterator __last,
4503	_OutputIterator __result)
4504	{
4505	// concept requirements
4506	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
4507	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
4508	typename iterator_traits<_InputIterator>::value_type>)
4509	__glibcxx_function_requires(_EqualityComparableConcept<
4510	typename iterator_traits<_InputIterator>::value_type>)
4511	__glibcxx_requires_valid_range(__first, __last);
4512
4513	if (__first == __last)
4514	return __result;
4515	return std::__unique_copy(__first, __last, __result,
4516	__gnu_cxx::__ops::__iter_equal_to_iter(),
4517	std::__iterator_category(__first),
4518	std::__iterator_category(__result));
4519	}
4520
4521	/**
4522	* @brief Copy a sequence, removing consecutive values using a predicate.
4523	* @ingroup mutating_algorithms
4524	* @param __first An input iterator.
4525	* @param __last An input iterator.
4526	* @param __result An output iterator.
4527	* @param __binary_pred A binary predicate.
4528	* @return An iterator designating the end of the resulting sequence.
4529	*
4530	* Copies each element in the range `[__first, __last)` to the range
4531	* beginning at `__result`, except that only the first element is copied
4532	* from groups of consecutive elements for which `__binary_pred` returns
4533	* true.
4534	* `unique_copy()` is stable, so the relative order of elements that are
4535	* copied is unchanged.
4536	*/
4537	// _GLIBCXX_RESOLVE_LIB_DEFECTS
4538	// DR 241. Does unique_copy() require CopyConstructible and Assignable?
4539	template<typename _InputIterator, typename _OutputIterator,
4540	typename _BinaryPredicate>
4541	_GLIBCXX20_CONSTEXPR
4542	inline _OutputIterator
4543	unique_copy(_InputIterator __first, _InputIterator __last,
4544	_OutputIterator __result,
4545	_BinaryPredicate __binary_pred)
4546	{
4547	// concept requirements -- predicates checked later
4548	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
4549	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
4550	typename iterator_traits<_InputIterator>::value_type>)
4551	__glibcxx_requires_valid_range(__first, __last);
4552
4553	if (__first == __last)
4554	return __result;
4555	return std::__unique_copy(__first, __last, __result,
4556	__gnu_cxx::__ops::__iter_comp_iter(__binary_pred),
4557	std::__iterator_category(__first),
4558	std::__iterator_category(__result));
4559	}
4560
4561	#if __cplusplus <= 201103L \|\| _GLIBCXX_USE_DEPRECATED
4562	#if _GLIBCXX_HOSTED
4563	/**
4564	* @brief Randomly shuffle the elements of a sequence.
4565	* @ingroup mutating_algorithms
4566	* @param __first A forward iterator.
4567	* @param __last A forward iterator.
4568	* @return Nothing.
4569	*
4570	* Reorder the elements in the range `[__first, __last)` using a random
4571	* distribution, so that every possible ordering of the sequence is
4572	* equally likely.
4573	*
4574	* @deprecated
4575	* Since C++17, `std::random_shuffle` is not part of the C++ standard.
4576	* Use `std::shuffle` instead, which was introduced in C++11.
4577	*/
4578	template<typename _RandomAccessIterator>
4579	_GLIBCXX14_DEPRECATED_SUGGEST("std::shuffle")
4580	inline void
4581	random_shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last)
4582	{
4583	// concept requirements
4584	__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
4585	_RandomAccessIterator>)
4586	__glibcxx_requires_valid_range(__first, __last);
4587
4588	if (__first != __last)
4589	for (_RandomAccessIterator __i = __first + `1`; __i != __last; ++__i)
4590	{
4591	// XXX rand() % N is not uniformly distributed
4592	_RandomAccessIterator __j = __first
4593	+ std::rand() % ((__i - __first) + `1`);
4594	if (__i != __j)
4595	std::iter_swap(__i, __j);
4596	}
4597	}
4598
4599	/**
4600	* @brief Shuffle the elements of a sequence using a random number
4601	* generator.
4602	* @ingroup mutating_algorithms
4603	* @param __first A forward iterator.
4604	* @param __last A forward iterator.
4605	* @param __rand The RNG functor or function.
4606	* @return Nothing.
4607	*
4608	* Reorders the elements in the range `[__first, __last)` using `__rand`
4609	* to provide a random distribution. Calling `__rand(N)` for a positive
4610	* integer `N` should return a randomly chosen integer from the
4611	* range `[0, N)`.
4612	*
4613	* @deprecated
4614	* Since C++17, `std::random_shuffle` is not part of the C++ standard.
4615	* Use `std::shuffle` instead, which was introduced in C++11.
4616	*/
4617	template<typename _RandomAccessIterator, typename _RandomNumberGenerator>
4618	_GLIBCXX14_DEPRECATED_SUGGEST("std::shuffle")
4619	void
4620	random_shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last,
4621	#if __cplusplus >= 201103L
4622	_RandomNumberGenerator&& __rand)
4623	#else
4624	_RandomNumberGenerator& __rand)
4625	#endif
4626	{
4627	// concept requirements
4628	__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
4629	_RandomAccessIterator>)
4630	__glibcxx_requires_valid_range(__first, __last);
4631
4632	if (__first == __last)
4633	return;
4634	for (_RandomAccessIterator __i = __first + `1`; __i != __last; ++__i)
4635	{
4636	_RandomAccessIterator __j = __first + __rand((__i - __first) + `1`);
4637	if (__i != __j)
4638	std::iter_swap(__i, __j);
4639	}
4640	}
4641	#endif // HOSTED
4642	#endif // <= C++11 \|\| USE_DEPRECATED
4643
4644	/**
4645	* @brief Move elements for which a predicate is true to the beginning
4646	* of a sequence.
4647	* @ingroup mutating_algorithms
4648	* @param __first A forward iterator.
4649	* @param __last A forward iterator.
4650	* @param __pred A predicate functor.
4651	* @return An iterator `middle` such that `__pred(i)` is true for each
4652	* iterator `i` in the range `[__first, middle)` and false for each `i`
4653	* in the range `[middle, __last)`.
4654	*
4655	* `__pred` must not modify its operand. `partition()` does not preserve
4656	* the relative ordering of elements in each group, use
4657	* `stable_partition()` if this is needed.
4658	*/
4659	template<typename _ForwardIterator, typename _Predicate>
4660	_GLIBCXX20_CONSTEXPR
4661	inline _ForwardIterator
4662	partition(_ForwardIterator __first, _ForwardIterator __last,
4663	_Predicate __pred)
4664	{
4665	// concept requirements
4666	__glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
4667	_ForwardIterator>)
4668	__glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
4669	typename iterator_traits<_ForwardIterator>::value_type>)
4670	__glibcxx_requires_valid_range(__first, __last);
4671
4672	return std::__partition(__first, __last, __pred,
4673	std::__iterator_category(__first));
4674	}
4675
4676
4677	/**
4678	* @brief Sort the smallest elements of a sequence.
4679	* @ingroup sorting_algorithms
4680	* @param __first An iterator.
4681	* @param __middle Another iterator.
4682	* @param __last Another iterator.
4683	* @return Nothing.
4684	*
4685	* Sorts the smallest `(__middle - __first)` elements in the range
4686	* `[first, last)` and moves them to the range `[__first, __middle)`. The
4687	* order of the remaining elements in the range `[__middle, __last)` is
4688	* unspecified.
4689	* After the sort if `i` and `j` are iterators in the range
4690	* `[__first, __middle)` such that `i` precedes `j` and `k` is an iterator
4691	* in the range `[__middle, __last)` then `j < i` and `k < i` are
4692	* both false.
4693	*/
4694	template<typename _RandomAccessIterator>
4695	_GLIBCXX20_CONSTEXPR
4696	inline void
4697	partial_sort(_RandomAccessIterator __first,
4698	_RandomAccessIterator __middle,
4699	_RandomAccessIterator __last)
4700	{
4701	// concept requirements
4702	__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
4703	_RandomAccessIterator>)
4704	__glibcxx_function_requires(_LessThanComparableConcept<
4705	typename iterator_traits<_RandomAccessIterator>::value_type>)
4706	__glibcxx_requires_valid_range(__first, __middle);
4707	__glibcxx_requires_valid_range(__middle, __last);
4708	__glibcxx_requires_irreflexive(__first, __last);
4709
4710	std::__partial_sort(__first, __middle, __last,
4711	__gnu_cxx::__ops::__iter_less_iter());
4712	}
4713
4714	/**
4715	* @brief Sort the smallest elements of a sequence using a predicate
4716	* for comparison.
4717	* @ingroup sorting_algorithms
4718	* @param __first An iterator.
4719	* @param __middle Another iterator.
4720	* @param __last Another iterator.
4721	* @param __comp A comparison functor.
4722	* @return Nothing.
4723	*
4724	* Sorts the smallest `(__middle - __first)` elements in the range
4725	* `[__first, __last)` and moves them to the range `[__first, __middle)`.
4726	* The order of the remaining elements in the range `[__middle, __last)` is
4727	* unspecified.
4728	* After the sort if `i` and `j` are iterators in the range
4729	* `[__first, __middle)` such that `i` precedes `j` and `k` is an iterator
4730	* in the range `[__middle, __last)` then `__comp(j, i)` and
4731	* `__comp(k, i)` are both false.
4732	*/
4733	template<typename _RandomAccessIterator, typename _Compare>
4734	_GLIBCXX20_CONSTEXPR
4735	inline void
4736	partial_sort(_RandomAccessIterator __first,
4737	_RandomAccessIterator __middle,
4738	_RandomAccessIterator __last,
4739	_Compare __comp)
4740	{
4741	// concept requirements
4742	__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
4743	_RandomAccessIterator>)
4744	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
4745	typename iterator_traits<_RandomAccessIterator>::value_type,
4746	typename iterator_traits<_RandomAccessIterator>::value_type>)
4747	__glibcxx_requires_valid_range(__first, __middle);
4748	__glibcxx_requires_valid_range(__middle, __last);
4749	__glibcxx_requires_irreflexive_pred(__first, __last, __comp);
4750
4751	std::__partial_sort(__first, __middle, __last,
4752	__gnu_cxx::__ops::__iter_comp_iter(__comp));
4753	}
4754
4755	/**
4756	* @brief Sort a sequence just enough to find a particular position.
4757	* @ingroup sorting_algorithms
4758	* @param __first An iterator.
4759	* @param __nth Another iterator.
4760	* @param __last Another iterator.
4761	* @return Nothing.
4762	*
4763	* Rearranges the elements in the range `[__first, __last)` so that `*__nth`
4764	* is the same element that would have been in that position had the
4765	* whole sequence been sorted. The elements either side of `*__nth` are
4766	* not completely sorted, but for any iterator `i` in the range
4767	* `[__first, __nth)` and any iterator `j` in the range `[__nth, __last)` it
4768	* holds that `j < i` is false.
4769	*/
4770	template<typename _RandomAccessIterator>
4771	_GLIBCXX20_CONSTEXPR
4772	inline void
4773	nth_element(_RandomAccessIterator __first, _RandomAccessIterator __nth,
4774	_RandomAccessIterator __last)
4775	{
4776	// concept requirements
4777	__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
4778	_RandomAccessIterator>)
4779	__glibcxx_function_requires(_LessThanComparableConcept<
4780	typename iterator_traits<_RandomAccessIterator>::value_type>)
4781	__glibcxx_requires_valid_range(__first, __nth);
4782	__glibcxx_requires_valid_range(__nth, __last);
4783	__glibcxx_requires_irreflexive(__first, __last);
4784
4785	if (__first == __last \|\| __nth == __last)
4786	return;
4787
4788	std::__introselect(__first, __nth, __last,
4789	std::__lg(__last - __first) * `2`,
4790	__gnu_cxx::__ops::__iter_less_iter());
4791	}
4792
4793	/**
4794	* @brief Sort a sequence just enough to find a particular position
4795	* using a predicate for comparison.
4796	* @ingroup sorting_algorithms
4797	* @param __first An iterator.
4798	* @param __nth Another iterator.
4799	* @param __last Another iterator.
4800	* @param __comp A comparison functor.
4801	* @return Nothing.
4802	*
4803	* Rearranges the elements in the range `[__first, __last)` so that `*__nth`
4804	* is the same element that would have been in that position had the
4805	* whole sequence been sorted. The elements either side of `*__nth` are
4806	* not completely sorted, but for any iterator `i` in the range
4807	* `[__first, __nth)` and any iterator `j` in the range `[__nth, __last)`
4808	* it holds that `__comp(j, i)` is false.
4809	*/
4810	template<typename _RandomAccessIterator, typename _Compare>
4811	_GLIBCXX20_CONSTEXPR
4812	inline void
4813	nth_element(_RandomAccessIterator __first, _RandomAccessIterator __nth,
4814	_RandomAccessIterator __last, _Compare __comp)
4815	{
4816	// concept requirements
4817	__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
4818	_RandomAccessIterator>)
4819	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
4820	typename iterator_traits<_RandomAccessIterator>::value_type,
4821	typename iterator_traits<_RandomAccessIterator>::value_type>)
4822	__glibcxx_requires_valid_range(__first, __nth);
4823	__glibcxx_requires_valid_range(__nth, __last);
4824	__glibcxx_requires_irreflexive_pred(__first, __last, __comp);
4825
4826	if (__first == __last \|\| __nth == __last)
4827	return;
4828
4829	std::__introselect(__first, __nth, __last,
4830	std::__lg(__last - __first) * `2`,
4831	__gnu_cxx::__ops::__iter_comp_iter(__comp));
4832	}
4833
4834	/**
4835	* @brief Sort the elements of a sequence.
4836	* @ingroup sorting_algorithms
4837	* @param __first An iterator.
4838	* @param __last Another iterator.
4839	* @return Nothing.
4840	*
4841	* Sorts the elements in the range `[__first, __last)` in ascending order,
4842	* such that for each iterator `i` in the range `[__first, __last - 1)`,
4843	* `(i+1) < i` is false.
4844	*
4845	* The relative ordering of equivalent elements is not preserved, use
4846	* `stable_sort()` if this is needed.
4847	*/
4848	template<typename _RandomAccessIterator>
4849	_GLIBCXX20_CONSTEXPR
4850	inline void
4851	sort(_RandomAccessIterator __first, _RandomAccessIterator __last)
4852	{
4853	// concept requirements
4854	__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
4855	_RandomAccessIterator>)
4856	__glibcxx_function_requires(_LessThanComparableConcept<
4857	typename iterator_traits<_RandomAccessIterator>::value_type>)
4858	__glibcxx_requires_valid_range(__first, __last);
4859	__glibcxx_requires_irreflexive(__first, __last);
4860
4861	std::__sort(__first, __last, __gnu_cxx::__ops::__iter_less_iter());
4862	}
4863
4864	/**
4865	* @brief Sort the elements of a sequence using a predicate for comparison.
4866	* @ingroup sorting_algorithms
4867	* @param __first An iterator.
4868	* @param __last Another iterator.
4869	* @param __comp A comparison functor.
4870	* @return Nothing.
4871	*
4872	* Sorts the elements in the range `[__first, __last)` in ascending order,
4873	* such that `__comp((i+1), i)` is false for every iterator `i` in the
4874	* range `[__first, __last - 1)`.
4875	*
4876	* The relative ordering of equivalent elements is not preserved, use
4877	* `stable_sort()` if this is needed.
4878	*/
4879	template<typename _RandomAccessIterator, typename _Compare>
4880	_GLIBCXX20_CONSTEXPR
4881	inline void
4882	sort(_RandomAccessIterator __first, _RandomAccessIterator __last,
4883	_Compare __comp)
4884	{
4885	// concept requirements
4886	__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
4887	_RandomAccessIterator>)
4888	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
4889	typename iterator_traits<_RandomAccessIterator>::value_type,
4890	typename iterator_traits<_RandomAccessIterator>::value_type>)
4891	__glibcxx_requires_valid_range(__first, __last);
4892	__glibcxx_requires_irreflexive_pred(__first, __last, __comp);
4893
4894	std::__sort(__first, __last, __gnu_cxx::__ops::__iter_comp_iter(__comp));
4895	}
4896
4897	template<typename _InputIterator1, typename _InputIterator2,
4898	typename _OutputIterator, typename _Compare>
4899	_GLIBCXX20_CONSTEXPR
4900	_OutputIterator
4901	__merge(_InputIterator1 __first1, _InputIterator1 __last1,
4902	_InputIterator2 __first2, _InputIterator2 __last2,
4903	_OutputIterator __result, _Compare __comp)
4904	{
4905	while (__first1 != __last1 && __first2 != __last2)
4906	{
4907	if (__comp(__first2, __first1))
4908	{
4909	__result = __first2;
4910	++__first2;
4911	}
4912	else
4913	{
4914	__result = __first1;
4915	++__first1;
4916	}
4917	++__result;
4918	}
4919	return std::copy(__first2, __last2,
4920	std::copy(__first1, __last1, __result));
4921	}
4922
4923	/**
4924	* @brief Merges two sorted ranges.
4925	* @ingroup sorting_algorithms
4926	* @param __first1 An iterator.
4927	* @param __first2 Another iterator.
4928	* @param __last1 Another iterator.
4929	* @param __last2 Another iterator.
4930	* @param __result An iterator pointing to the end of the merged range.
4931	* @return An output iterator equal to @p __result + (__last1 - __first1)
4932	* + (__last2 - __first2).
4933	*
4934	* Merges the ranges @p [__first1,__last1) and @p [__first2,__last2) into
4935	* the sorted range @p [__result, __result + (__last1-__first1) +
4936	* (__last2-__first2)). Both input ranges must be sorted, and the
4937	* output range must not overlap with either of the input ranges.
4938	* The sort is @e stable, that is, for equivalent elements in the
4939	* two ranges, elements from the first range will always come
4940	* before elements from the second.
4941	*/
4942	template<typename _InputIterator1, typename _InputIterator2,
4943	typename _OutputIterator>
4944	_GLIBCXX20_CONSTEXPR
4945	inline _OutputIterator
4946	merge(_InputIterator1 __first1, _InputIterator1 __last1,
4947	_InputIterator2 __first2, _InputIterator2 __last2,
4948	_OutputIterator __result)
4949	{
4950	// concept requirements
4951	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
4952	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
4953	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
4954	typename iterator_traits<_InputIterator1>::value_type>)
4955	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
4956	typename iterator_traits<_InputIterator2>::value_type>)
4957	__glibcxx_function_requires(_LessThanOpConcept<
4958	typename iterator_traits<_InputIterator2>::value_type,
4959	typename iterator_traits<_InputIterator1>::value_type>)
4960	__glibcxx_requires_sorted_set(__first1, __last1, __first2);
4961	__glibcxx_requires_sorted_set(__first2, __last2, __first1);
4962	__glibcxx_requires_irreflexive2(__first1, __last1);
4963	__glibcxx_requires_irreflexive2(__first2, __last2);
4964
4965	return _GLIBCXX_STD_A::__merge(__first1, __last1,
4966	__first2, __last2, __result,
4967	__gnu_cxx::__ops::__iter_less_iter());
4968	}
4969
4970	/**
4971	* @brief Merges two sorted ranges.
4972	* @ingroup sorting_algorithms
4973	* @param __first1 An iterator.
4974	* @param __first2 Another iterator.
4975	* @param __last1 Another iterator.
4976	* @param __last2 Another iterator.
4977	* @param __result An iterator pointing to the end of the merged range.
4978	* @param __comp A functor to use for comparisons.
4979	* @return An output iterator equal to @p __result + (__last1 - __first1)
4980	* + (__last2 - __first2).
4981	*
4982	* Merges the ranges @p [__first1,__last1) and @p [__first2,__last2) into
4983	* the sorted range @p [__result, __result + (__last1-__first1) +
4984	* (__last2-__first2)). Both input ranges must be sorted, and the
4985	* output range must not overlap with either of the input ranges.
4986	* The sort is @e stable, that is, for equivalent elements in the
4987	* two ranges, elements from the first range will always come
4988	* before elements from the second.
4989	*
4990	* The comparison function should have the same effects on ordering as
4991	* the function used for the initial sort.
4992	*/
4993	template<typename _InputIterator1, typename _InputIterator2,
4994	typename _OutputIterator, typename _Compare>
4995	_GLIBCXX20_CONSTEXPR
4996	inline _OutputIterator
4997	merge(_InputIterator1 __first1, _InputIterator1 __last1,
4998	_InputIterator2 __first2, _InputIterator2 __last2,
4999	_OutputIterator __result, _Compare __comp)
5000	{
5001	// concept requirements
5002	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
5003	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
5004	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
5005	typename iterator_traits<_InputIterator1>::value_type>)
5006	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
5007	typename iterator_traits<_InputIterator2>::value_type>)
5008	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
5009	typename iterator_traits<_InputIterator2>::value_type,
5010	typename iterator_traits<_InputIterator1>::value_type>)
5011	__glibcxx_requires_sorted_set_pred(__first1, __last1, __first2, __comp);
5012	__glibcxx_requires_sorted_set_pred(__first2, __last2, __first1, __comp);
5013	__glibcxx_requires_irreflexive_pred2(__first1, __last1, __comp);
5014	__glibcxx_requires_irreflexive_pred2(__first2, __last2, __comp);
5015
5016	return _GLIBCXX_STD_A::__merge(__first1, __last1,
5017	__first2, __last2, __result,
5018	__gnu_cxx::__ops::__iter_comp_iter(__comp));
5019	}
5020
5021	template<typename _RandomAccessIterator, typename _Compare>
5022	inline void
5023	__stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last,
5024	_Compare __comp)
5025	{
5026	typedef typename iterator_traits<_RandomAccessIterator>::value_type
5027	_ValueType;
5028	typedef typename iterator_traits<_RandomAccessIterator>::difference_type
5029	_DistanceType;
5030
5031	if (__first == __last)
5032	return;
5033
5034	#if _GLIBCXX_HOSTED
5035	typedef _Temporary_buffer<_RandomAccessIterator, _ValueType> _TmpBuf;
5036	// __stable_sort_adaptive sorts the range in two halves,
5037	// so the buffer only needs to fit half the range at once.
5038	_TmpBuf __buf(__first, (__last - __first + `1`) / `2`);
5039
5040	if (__builtin_expect(__buf.requested_size() == __buf.size(), true))
5041	std::__stable_sort_adaptive(__first,
5042	__first + _DistanceType(__buf.size()),
5043	__last, __buf.begin(), __comp);
5044	else if (__builtin_expect(__buf.begin() == `0`, false))
5045	std::__inplace_stable_sort(__first, __last, __comp);
5046	else
5047	std::__stable_sort_adaptive_resize(__first, __last, __buf.begin(),
5048	_DistanceType(__buf.size()), __comp);
5049	#else
5050	std::__inplace_stable_sort(__first, __last, __comp);
5051	#endif
5052	}
5053
5054	/**
5055	* @brief Sort the elements of a sequence, preserving the relative order
5056	* of equivalent elements.
5057	* @ingroup sorting_algorithms
5058	* @param __first An iterator.
5059	* @param __last Another iterator.
5060	* @return Nothing.
5061	*
5062	* Sorts the elements in the range @p [__first,__last) in ascending order,
5063	* such that for each iterator @p i in the range @p [__first,__last-1),
5064	* @p (i+1)<i is false.
5065	*
5066	* The relative ordering of equivalent elements is preserved, so any two
5067	* elements @p x and @p y in the range @p [__first,__last) such that
5068	* @p x<y is false and @p y<x is false will have the same relative
5069	* ordering after calling @p stable_sort().
5070	*/
5071	template<typename _RandomAccessIterator>
5072	inline void
5073	stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last)
5074	{
5075	// concept requirements
5076	__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
5077	_RandomAccessIterator>)
5078	__glibcxx_function_requires(_LessThanComparableConcept<
5079	typename iterator_traits<_RandomAccessIterator>::value_type>)
5080	__glibcxx_requires_valid_range(__first, __last);
5081	__glibcxx_requires_irreflexive(__first, __last);
5082
5083	_GLIBCXX_STD_A::__stable_sort(__first, __last,
5084	__gnu_cxx::__ops::__iter_less_iter());
5085	}
5086
5087	/**
5088	* @brief Sort the elements of a sequence using a predicate for comparison,
5089	* preserving the relative order of equivalent elements.
5090	* @ingroup sorting_algorithms
5091	* @param __first An iterator.
5092	* @param __last Another iterator.
5093	* @param __comp A comparison functor.
5094	* @return Nothing.
5095	*
5096	* Sorts the elements in the range @p [__first,__last) in ascending order,
5097	* such that for each iterator @p i in the range @p [__first,__last-1),
5098	* @p __comp((i+1),i) is false.
5099	*
5100	* The relative ordering of equivalent elements is preserved, so any two
5101	* elements @p x and @p y in the range @p [__first,__last) such that
5102	* @p __comp(x,y) is false and @p __comp(y,x) is false will have the same
5103	* relative ordering after calling @p stable_sort().
5104	*/
5105	template<typename _RandomAccessIterator, typename _Compare>
5106	inline void
5107	stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last,
5108	_Compare __comp)
5109	{
5110	// concept requirements
5111	__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
5112	_RandomAccessIterator>)
5113	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
5114	typename iterator_traits<_RandomAccessIterator>::value_type,
5115	typename iterator_traits<_RandomAccessIterator>::value_type>)
5116	__glibcxx_requires_valid_range(__first, __last);
5117	__glibcxx_requires_irreflexive_pred(__first, __last, __comp);
5118
5119	_GLIBCXX_STD_A::__stable_sort(__first, __last,
5120	__gnu_cxx::__ops::__iter_comp_iter(__comp));
5121	}
5122
5123	template<typename _InputIterator1, typename _InputIterator2,
5124	typename _OutputIterator,
5125	typename _Compare>
5126	_GLIBCXX20_CONSTEXPR
5127	_OutputIterator
5128	__set_union(_InputIterator1 __first1, _InputIterator1 __last1,
5129	_InputIterator2 __first2, _InputIterator2 __last2,
5130	_OutputIterator __result, _Compare __comp)
5131	{
5132	while (__first1 != __last1 && __first2 != __last2)
5133	{
5134	if (__comp(__first1, __first2))
5135	{
5136	__result = __first1;
5137	++__first1;
5138	}
5139	else if (__comp(__first2, __first1))
5140	{
5141	__result = __first2;
5142	++__first2;
5143	}
5144	else
5145	{
5146	__result = __first1;
5147	++__first1;
5148	++__first2;
5149	}
5150	++__result;
5151	}
5152	return std::copy(__first2, __last2,
5153	std::copy(__first1, __last1, __result));
5154	}
5155
5156	/**
5157	* @brief Return the union of two sorted ranges.
5158	* @ingroup set_algorithms
5159	* @param __first1 Start of first range.
5160	* @param __last1 End of first range.
5161	* @param __first2 Start of second range.
5162	* @param __last2 End of second range.
5163	* @param __result Start of output range.
5164	* @return End of the output range.
5165	* @ingroup set_algorithms
5166	*
5167	* This operation iterates over both ranges, copying elements present in
5168	* each range in order to the output range. Iterators increment for each
5169	* range. When the current element of one range is less than the other,
5170	* that element is copied and the iterator advanced. If an element is
5171	* contained in both ranges, the element from the first range is copied and
5172	* both ranges advance. The output range may not overlap either input
5173	* range.
5174	*/
5175	template<typename _InputIterator1, typename _InputIterator2,
5176	typename _OutputIterator>
5177	_GLIBCXX20_CONSTEXPR
5178	inline _OutputIterator
5179	set_union(_InputIterator1 __first1, _InputIterator1 __last1,
5180	_InputIterator2 __first2, _InputIterator2 __last2,
5181	_OutputIterator __result)
5182	{
5183	// concept requirements
5184	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
5185	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
5186	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
5187	typename iterator_traits<_InputIterator1>::value_type>)
5188	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
5189	typename iterator_traits<_InputIterator2>::value_type>)
5190	__glibcxx_function_requires(_LessThanOpConcept<
5191	typename iterator_traits<_InputIterator1>::value_type,
5192	typename iterator_traits<_InputIterator2>::value_type>)
5193	__glibcxx_function_requires(_LessThanOpConcept<
5194	typename iterator_traits<_InputIterator2>::value_type,
5195	typename iterator_traits<_InputIterator1>::value_type>)
5196	__glibcxx_requires_sorted_set(__first1, __last1, __first2);
5197	__glibcxx_requires_sorted_set(__first2, __last2, __first1);
5198	__glibcxx_requires_irreflexive2(__first1, __last1);
5199	__glibcxx_requires_irreflexive2(__first2, __last2);
5200
5201	return _GLIBCXX_STD_A::__set_union(__first1, __last1,
5202	__first2, __last2, __result,
5203	__gnu_cxx::__ops::__iter_less_iter());
5204	}
5205
5206	/**
5207	* @brief Return the union of two sorted ranges using a comparison functor.
5208	* @ingroup set_algorithms
5209	* @param __first1 Start of first range.
5210	* @param __last1 End of first range.
5211	* @param __first2 Start of second range.
5212	* @param __last2 End of second range.
5213	* @param __result Start of output range.
5214	* @param __comp The comparison functor.
5215	* @return End of the output range.
5216	* @ingroup set_algorithms
5217	*
5218	* This operation iterates over both ranges, copying elements present in
5219	* each range in order to the output range. Iterators increment for each
5220	* range. When the current element of one range is less than the other
5221	* according to @p __comp, that element is copied and the iterator advanced.
5222	* If an equivalent element according to @p __comp is contained in both
5223	* ranges, the element from the first range is copied and both ranges
5224	* advance. The output range may not overlap either input range.
5225	*/
5226	template<typename _InputIterator1, typename _InputIterator2,
5227	typename _OutputIterator, typename _Compare>
5228	_GLIBCXX20_CONSTEXPR
5229	inline _OutputIterator
5230	set_union(_InputIterator1 __first1, _InputIterator1 __last1,
5231	_InputIterator2 __first2, _InputIterator2 __last2,
5232	_OutputIterator __result, _Compare __comp)
5233	{
5234	// concept requirements
5235	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
5236	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
5237	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
5238	typename iterator_traits<_InputIterator1>::value_type>)
5239	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
5240	typename iterator_traits<_InputIterator2>::value_type>)
5241	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
5242	typename iterator_traits<_InputIterator1>::value_type,
5243	typename iterator_traits<_InputIterator2>::value_type>)
5244	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
5245	typename iterator_traits<_InputIterator2>::value_type,
5246	typename iterator_traits<_InputIterator1>::value_type>)
5247	__glibcxx_requires_sorted_set_pred(__first1, __last1, __first2, __comp);
5248	__glibcxx_requires_sorted_set_pred(__first2, __last2, __first1, __comp);
5249	__glibcxx_requires_irreflexive_pred2(__first1, __last1, __comp);
5250	__glibcxx_requires_irreflexive_pred2(__first2, __last2, __comp);
5251
5252	return _GLIBCXX_STD_A::__set_union(__first1, __last1,
5253	__first2, __last2, __result,
5254	__gnu_cxx::__ops::__iter_comp_iter(__comp));
5255	}
5256
5257	template<typename _InputIterator1, typename _InputIterator2,
5258	typename _OutputIterator,
5259	typename _Compare>
5260	_GLIBCXX20_CONSTEXPR
5261	_OutputIterator
5262	__set_intersection(_InputIterator1 __first1, _InputIterator1 __last1,
5263	_InputIterator2 __first2, _InputIterator2 __last2,
5264	_OutputIterator __result, _Compare __comp)
5265	{
5266	while (__first1 != __last1 && __first2 != __last2)
5267	if (__comp(__first1, __first2))
5268	++__first1;
5269	else if (__comp(__first2, __first1))
5270	++__first2;
5271	else
5272	{
5273	__result = __first1;
5274	++__first1;
5275	++__first2;
5276	++__result;
5277	}
5278	return __result;
5279	}
5280
5281	/**
5282	* @brief Return the intersection of two sorted ranges.
5283	* @ingroup set_algorithms
5284	* @param __first1 Start of first range.
5285	* @param __last1 End of first range.
5286	* @param __first2 Start of second range.
5287	* @param __last2 End of second range.
5288	* @param __result Start of output range.
5289	* @return End of the output range.
5290	* @ingroup set_algorithms
5291	*
5292	* This operation iterates over both ranges, copying elements present in
5293	* both ranges in order to the output range. Iterators increment for each
5294	* range. When the current element of one range is less than the other,
5295	* that iterator advances. If an element is contained in both ranges, the
5296	* element from the first range is copied and both ranges advance. The
5297	* output range may not overlap either input range.
5298	*/
5299	template<typename _InputIterator1, typename _InputIterator2,
5300	typename _OutputIterator>
5301	_GLIBCXX20_CONSTEXPR
5302	inline _OutputIterator
5303	set_intersection(_InputIterator1 __first1, _InputIterator1 __last1,
5304	_InputIterator2 __first2, _InputIterator2 __last2,
5305	_OutputIterator __result)
5306	{
5307	// concept requirements
5308	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
5309	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
5310	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
5311	typename iterator_traits<_InputIterator1>::value_type>)
5312	__glibcxx_function_requires(_LessThanOpConcept<
5313	typename iterator_traits<_InputIterator1>::value_type,
5314	typename iterator_traits<_InputIterator2>::value_type>)
5315	__glibcxx_function_requires(_LessThanOpConcept<
5316	typename iterator_traits<_InputIterator2>::value_type,
5317	typename iterator_traits<_InputIterator1>::value_type>)
5318	__glibcxx_requires_sorted_set(__first1, __last1, __first2);
5319	__glibcxx_requires_sorted_set(__first2, __last2, __first1);
5320	__glibcxx_requires_irreflexive2(__first1, __last1);
5321	__glibcxx_requires_irreflexive2(__first2, __last2);
5322
5323	return _GLIBCXX_STD_A::__set_intersection(__first1, __last1,
5324	__first2, __last2, __result,
5325	__gnu_cxx::__ops::__iter_less_iter());
5326	}
5327
5328	/**
5329	* @brief Return the intersection of two sorted ranges using comparison
5330	* functor.
5331	* @ingroup set_algorithms
5332	* @param __first1 Start of first range.
5333	* @param __last1 End of first range.
5334	* @param __first2 Start of second range.
5335	* @param __last2 End of second range.
5336	* @param __result Start of output range.
5337	* @param __comp The comparison functor.
5338	* @return End of the output range.
5339	* @ingroup set_algorithms
5340	*
5341	* This operation iterates over both ranges, copying elements present in
5342	* both ranges in order to the output range. Iterators increment for each
5343	* range. When the current element of one range is less than the other
5344	* according to @p __comp, that iterator advances. If an element is
5345	* contained in both ranges according to @p __comp, the element from the
5346	* first range is copied and both ranges advance. The output range may not
5347	* overlap either input range.
5348	*/
5349	template<typename _InputIterator1, typename _InputIterator2,
5350	typename _OutputIterator, typename _Compare>
5351	_GLIBCXX20_CONSTEXPR
5352	inline _OutputIterator
5353	set_intersection(_InputIterator1 __first1, _InputIterator1 __last1,
5354	_InputIterator2 __first2, _InputIterator2 __last2,
5355	_OutputIterator __result, _Compare __comp)
5356	{
5357	// concept requirements
5358	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
5359	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
5360	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
5361	typename iterator_traits<_InputIterator1>::value_type>)
5362	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
5363	typename iterator_traits<_InputIterator1>::value_type,
5364	typename iterator_traits<_InputIterator2>::value_type>)
5365	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
5366	typename iterator_traits<_InputIterator2>::value_type,
5367	typename iterator_traits<_InputIterator1>::value_type>)
5368	__glibcxx_requires_sorted_set_pred(__first1, __last1, __first2, __comp);
5369	__glibcxx_requires_sorted_set_pred(__first2, __last2, __first1, __comp);
5370	__glibcxx_requires_irreflexive_pred2(__first1, __last1, __comp);
5371	__glibcxx_requires_irreflexive_pred2(__first2, __last2, __comp);
5372
5373	return _GLIBCXX_STD_A::__set_intersection(__first1, __last1,
5374	__first2, __last2, __result,
5375	__gnu_cxx::__ops::__iter_comp_iter(__comp));
5376	}
5377
5378	template<typename _InputIterator1, typename _InputIterator2,
5379	typename _OutputIterator,
5380	typename _Compare>
5381	_GLIBCXX20_CONSTEXPR
5382	_OutputIterator
5383	__set_difference(_InputIterator1 __first1, _InputIterator1 __last1,
5384	_InputIterator2 __first2, _InputIterator2 __last2,
5385	_OutputIterator __result, _Compare __comp)
5386	{
5387	while (__first1 != __last1 && __first2 != __last2)
5388	if (__comp(__first1, __first2))
5389	{
5390	__result = __first1;
5391	++__first1;
5392	++__result;
5393	}
5394	else if (__comp(__first2, __first1))
5395	++__first2;
5396	else
5397	{
5398	++__first1;
5399	++__first2;
5400	}
5401	return std::copy(__first1, __last1, __result);
5402	}
5403
5404	/**
5405	* @brief Return the difference of two sorted ranges.
5406	* @ingroup set_algorithms
5407	* @param __first1 Start of first range.
5408	* @param __last1 End of first range.
5409	* @param __first2 Start of second range.
5410	* @param __last2 End of second range.
5411	* @param __result Start of output range.
5412	* @return End of the output range.
5413	* @ingroup set_algorithms
5414	*
5415	* This operation iterates over both ranges, copying elements present in
5416	* the first range but not the second in order to the output range.
5417	* Iterators increment for each range. When the current element of the
5418	* first range is less than the second, that element is copied and the
5419	* iterator advances. If the current element of the second range is less,
5420	* the iterator advances, but no element is copied. If an element is
5421	* contained in both ranges, no elements are copied and both ranges
5422	* advance. The output range may not overlap either input range.
5423	*/
5424	template<typename _InputIterator1, typename _InputIterator2,
5425	typename _OutputIterator>
5426	_GLIBCXX20_CONSTEXPR
5427	inline _OutputIterator
5428	set_difference(_InputIterator1 __first1, _InputIterator1 __last1,
5429	_InputIterator2 __first2, _InputIterator2 __last2,
5430	_OutputIterator __result)
5431	{
5432	// concept requirements
5433	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
5434	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
5435	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
5436	typename iterator_traits<_InputIterator1>::value_type>)
5437	__glibcxx_function_requires(_LessThanOpConcept<
5438	typename iterator_traits<_InputIterator1>::value_type,
5439	typename iterator_traits<_InputIterator2>::value_type>)
5440	__glibcxx_function_requires(_LessThanOpConcept<
5441	typename iterator_traits<_InputIterator2>::value_type,
5442	typename iterator_traits<_InputIterator1>::value_type>)
5443	__glibcxx_requires_sorted_set(__first1, __last1, __first2);
5444	__glibcxx_requires_sorted_set(__first2, __last2, __first1);
5445	__glibcxx_requires_irreflexive2(__first1, __last1);
5446	__glibcxx_requires_irreflexive2(__first2, __last2);
5447
5448	return _GLIBCXX_STD_A::__set_difference(__first1, __last1,
5449	__first2, __last2, __result,
5450	__gnu_cxx::__ops::__iter_less_iter());
5451	}
5452
5453	/**
5454	* @brief Return the difference of two sorted ranges using comparison
5455	* functor.
5456	* @ingroup set_algorithms
5457	* @param __first1 Start of first range.
5458	* @param __last1 End of first range.
5459	* @param __first2 Start of second range.
5460	* @param __last2 End of second range.
5461	* @param __result Start of output range.
5462	* @param __comp The comparison functor.
5463	* @return End of the output range.
5464	* @ingroup set_algorithms
5465	*
5466	* This operation iterates over both ranges, copying elements present in
5467	* the first range but not the second in order to the output range.
5468	* Iterators increment for each range. When the current element of the
5469	* first range is less than the second according to @p __comp, that element
5470	* is copied and the iterator advances. If the current element of the
5471	* second range is less, no element is copied and the iterator advances.
5472	* If an element is contained in both ranges according to @p __comp, no
5473	* elements are copied and both ranges advance. The output range may not
5474	* overlap either input range.
5475	*/
5476	template<typename _InputIterator1, typename _InputIterator2,
5477	typename _OutputIterator, typename _Compare>
5478	_GLIBCXX20_CONSTEXPR
5479	inline _OutputIterator
5480	set_difference(_InputIterator1 __first1, _InputIterator1 __last1,
5481	_InputIterator2 __first2, _InputIterator2 __last2,
5482	_OutputIterator __result, _Compare __comp)
5483	{
5484	// concept requirements
5485	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
5486	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
5487	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
5488	typename iterator_traits<_InputIterator1>::value_type>)
5489	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
5490	typename iterator_traits<_InputIterator1>::value_type,
5491	typename iterator_traits<_InputIterator2>::value_type>)
5492	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
5493	typename iterator_traits<_InputIterator2>::value_type,
5494	typename iterator_traits<_InputIterator1>::value_type>)
5495	__glibcxx_requires_sorted_set_pred(__first1, __last1, __first2, __comp);
5496	__glibcxx_requires_sorted_set_pred(__first2, __last2, __first1, __comp);
5497	__glibcxx_requires_irreflexive_pred2(__first1, __last1, __comp);
5498	__glibcxx_requires_irreflexive_pred2(__first2, __last2, __comp);
5499
5500	return _GLIBCXX_STD_A::__set_difference(__first1, __last1,
5501	__first2, __last2, __result,
5502	__gnu_cxx::__ops::__iter_comp_iter(__comp));
5503	}
5504
5505	template<typename _InputIterator1, typename _InputIterator2,
5506	typename _OutputIterator,
5507	typename _Compare>
5508	_GLIBCXX20_CONSTEXPR
5509	_OutputIterator
5510	__set_symmetric_difference(_InputIterator1 __first1,
5511	_InputIterator1 __last1,
5512	_InputIterator2 __first2,
5513	_InputIterator2 __last2,
5514	_OutputIterator __result,
5515	_Compare __comp)
5516	{
5517	while (__first1 != __last1 && __first2 != __last2)
5518	if (__comp(__first1, __first2))
5519	{
5520	__result = __first1;
5521	++__first1;
5522	++__result;
5523	}
5524	else if (__comp(__first2, __first1))
5525	{
5526	__result = __first2;
5527	++__first2;
5528	++__result;
5529	}
5530	else
5531	{
5532	++__first1;
5533	++__first2;
5534	}
5535	return std::copy(__first2, __last2,
5536	std::copy(__first1, __last1, __result));
5537	}
5538
5539	/**
5540	* @brief Return the symmetric difference of two sorted ranges.
5541	* @ingroup set_algorithms
5542	* @param __first1 Start of first range.
5543	* @param __last1 End of first range.
5544	* @param __first2 Start of second range.
5545	* @param __last2 End of second range.
5546	* @param __result Start of output range.
5547	* @return End of the output range.
5548	* @ingroup set_algorithms
5549	*
5550	* This operation iterates over both ranges, copying elements present in
5551	* one range but not the other in order to the output range. Iterators
5552	* increment for each range. When the current element of one range is less
5553	* than the other, that element is copied and the iterator advances. If an
5554	* element is contained in both ranges, no elements are copied and both
5555	* ranges advance. The output range may not overlap either input range.
5556	*/
5557	template<typename _InputIterator1, typename _InputIterator2,
5558	typename _OutputIterator>
5559	_GLIBCXX20_CONSTEXPR
5560	inline _OutputIterator
5561	set_symmetric_difference(_InputIterator1 __first1, _InputIterator1 __last1,
5562	_InputIterator2 __first2, _InputIterator2 __last2,
5563	_OutputIterator __result)
5564	{
5565	// concept requirements
5566	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
5567	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
5568	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
5569	typename iterator_traits<_InputIterator1>::value_type>)
5570	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
5571	typename iterator_traits<_InputIterator2>::value_type>)
5572	__glibcxx_function_requires(_LessThanOpConcept<
5573	typename iterator_traits<_InputIterator1>::value_type,
5574	typename iterator_traits<_InputIterator2>::value_type>)
5575	__glibcxx_function_requires(_LessThanOpConcept<
5576	typename iterator_traits<_InputIterator2>::value_type,
5577	typename iterator_traits<_InputIterator1>::value_type>)
5578	__glibcxx_requires_sorted_set(__first1, __last1, __first2);
5579	__glibcxx_requires_sorted_set(__first2, __last2, __first1);
5580	__glibcxx_requires_irreflexive2(__first1, __last1);
5581	__glibcxx_requires_irreflexive2(__first2, __last2);
5582
5583	return _GLIBCXX_STD_A::__set_symmetric_difference(__first1, __last1,
5584	__first2, __last2, __result,
5585	__gnu_cxx::__ops::__iter_less_iter());
5586	}
5587
5588	/**
5589	* @brief Return the symmetric difference of two sorted ranges using
5590	* comparison functor.
5591	* @ingroup set_algorithms
5592	* @param __first1 Start of first range.
5593	* @param __last1 End of first range.
5594	* @param __first2 Start of second range.
5595	* @param __last2 End of second range.
5596	* @param __result Start of output range.
5597	* @param __comp The comparison functor.
5598	* @return End of the output range.
5599	* @ingroup set_algorithms
5600	*
5601	* This operation iterates over both ranges, copying elements present in
5602	* one range but not the other in order to the output range. Iterators
5603	* increment for each range. When the current element of one range is less
5604	* than the other according to @p comp, that element is copied and the
5605	* iterator advances. If an element is contained in both ranges according
5606	* to @p __comp, no elements are copied and both ranges advance. The output
5607	* range may not overlap either input range.
5608	*/
5609	template<typename _InputIterator1, typename _InputIterator2,
5610	typename _OutputIterator, typename _Compare>
5611	_GLIBCXX20_CONSTEXPR
5612	inline _OutputIterator
5613	set_symmetric_difference(_InputIterator1 __first1, _InputIterator1 __last1,
5614	_InputIterator2 __first2, _InputIterator2 __last2,
5615	_OutputIterator __result,
5616	_Compare __comp)
5617	{
5618	// concept requirements
5619	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
5620	__glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
5621	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
5622	typename iterator_traits<_InputIterator1>::value_type>)
5623	__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
5624	typename iterator_traits<_InputIterator2>::value_type>)
5625	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
5626	typename iterator_traits<_InputIterator1>::value_type,
5627	typename iterator_traits<_InputIterator2>::value_type>)
5628	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
5629	typename iterator_traits<_InputIterator2>::value_type,
5630	typename iterator_traits<_InputIterator1>::value_type>)
5631	__glibcxx_requires_sorted_set_pred(__first1, __last1, __first2, __comp);
5632	__glibcxx_requires_sorted_set_pred(__first2, __last2, __first1, __comp);
5633	__glibcxx_requires_irreflexive_pred2(__first1, __last1, __comp);
5634	__glibcxx_requires_irreflexive_pred2(__first2, __last2, __comp);
5635
5636	return _GLIBCXX_STD_A::__set_symmetric_difference(__first1, __last1,
5637	__first2, __last2, __result,
5638	__gnu_cxx::__ops::__iter_comp_iter(__comp));
5639	}
5640
5641	template<typename _ForwardIterator, typename _Compare>
5642	_GLIBCXX14_CONSTEXPR
5643	_ForwardIterator
5644	__min_element(_ForwardIterator __first, _ForwardIterator __last,
5645	_Compare __comp)
5646	{
5647	if (__first == __last)
5648	return __first;
5649	_ForwardIterator __result = __first;
5650	while (++__first != __last)
5651	if (__comp(__first, __result))
5652	__result = __first;
5653	return __result;
5654	}
5655
5656	/**
5657	* @brief Return the minimum element in a range.
5658	* @ingroup sorting_algorithms
5659	* @param __first Start of range.
5660	* @param __last End of range.
5661	* @return Iterator referencing the first instance of the smallest value.
5662	*/
5663	template<typename _ForwardIterator>
5664	_GLIBCXX14_CONSTEXPR
5665	_ForwardIterator
5666	inline min_element(_ForwardIterator __first, _ForwardIterator __last)
5667	{
5668	// concept requirements
5669	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
5670	__glibcxx_function_requires(_LessThanComparableConcept<
5671	typename iterator_traits<_ForwardIterator>::value_type>)
5672	__glibcxx_requires_valid_range(__first, __last);
5673	__glibcxx_requires_irreflexive(__first, __last);
5674
5675	return _GLIBCXX_STD_A::__min_element(__first, __last,
5676	__gnu_cxx::__ops::__iter_less_iter());
5677	}
5678
5679	/**
5680	* @brief Return the minimum element in a range using comparison functor.
5681	* @ingroup sorting_algorithms
5682	* @param __first Start of range.
5683	* @param __last End of range.
5684	* @param __comp Comparison functor.
5685	* @return Iterator referencing the first instance of the smallest value
5686	* according to __comp.
5687	*/
5688	template<typename _ForwardIterator, typename _Compare>
5689	_GLIBCXX14_CONSTEXPR
5690	inline _ForwardIterator
5691	min_element(_ForwardIterator __first, _ForwardIterator __last,
5692	_Compare __comp)
5693	{
5694	// concept requirements
5695	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
5696	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
5697	typename iterator_traits<_ForwardIterator>::value_type,
5698	typename iterator_traits<_ForwardIterator>::value_type>)
5699	__glibcxx_requires_valid_range(__first, __last);
5700	__glibcxx_requires_irreflexive_pred(__first, __last, __comp);
5701
5702	return _GLIBCXX_STD_A::__min_element(__first, __last,
5703	__gnu_cxx::__ops::__iter_comp_iter(__comp));
5704	}
5705
5706	template<typename _ForwardIterator, typename _Compare>
5707	_GLIBCXX14_CONSTEXPR
5708	_ForwardIterator
5709	__max_element(_ForwardIterator __first, _ForwardIterator __last,
5710	_Compare __comp)
5711	{
5712	if (__first == __last) return __first;
5713	_ForwardIterator __result = __first;
5714	while (++__first != __last)
5715	if (__comp(__result, __first))
5716	__result = __first;
5717	return __result;
5718	}
5719
5720	/**
5721	* @brief Return the maximum element in a range.
5722	* @ingroup sorting_algorithms
5723	* @param __first Start of range.
5724	* @param __last End of range.
5725	* @return Iterator referencing the first instance of the largest value.
5726	*/
5727	template<typename _ForwardIterator>
5728	_GLIBCXX14_CONSTEXPR
5729	inline _ForwardIterator
5730	max_element(_ForwardIterator __first, _ForwardIterator __last)
5731	{
5732	// concept requirements
5733	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
5734	__glibcxx_function_requires(_LessThanComparableConcept<
5735	typename iterator_traits<_ForwardIterator>::value_type>)
5736	__glibcxx_requires_valid_range(__first, __last);
5737	__glibcxx_requires_irreflexive(__first, __last);
5738
5739	return _GLIBCXX_STD_A::__max_element(__first, __last,
5740	__gnu_cxx::__ops::__iter_less_iter());
5741	}
5742
5743	/**
5744	* @brief Return the maximum element in a range using comparison functor.
5745	* @ingroup sorting_algorithms
5746	* @param __first Start of range.
5747	* @param __last End of range.
5748	* @param __comp Comparison functor.
5749	* @return Iterator referencing the first instance of the largest value
5750	* according to __comp.
5751	*/
5752	template<typename _ForwardIterator, typename _Compare>
5753	_GLIBCXX14_CONSTEXPR
5754	inline _ForwardIterator
5755	max_element(_ForwardIterator __first, _ForwardIterator __last,
5756	_Compare __comp)
5757	{
5758	// concept requirements
5759	__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
5760	__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
5761	typename iterator_traits<_ForwardIterator>::value_type,
5762	typename iterator_traits<_ForwardIterator>::value_type>)
5763	__glibcxx_requires_valid_range(__first, __last);
5764	__glibcxx_requires_irreflexive_pred(__first, __last, __comp);
5765
5766	return _GLIBCXX_STD_A::__max_element(__first, __last,
5767	__gnu_cxx::__ops::__iter_comp_iter(__comp));
5768	}
5769
5770	#if __cplusplus >= 201103L
5771	// N2722 + DR 915.
5772	template<typename _Tp>
5773	_GLIBCXX14_CONSTEXPR
5774	inline _Tp
5775	min(initializer_list<_Tp> __l)
5776	{
5777	__glibcxx_requires_irreflexive(__l.begin(), __l.end());
5778	return *_GLIBCXX_STD_A::__min_element(__l.begin(), __l.end(),
5779	__gnu_cxx::__ops::__iter_less_iter());
5780	}
5781
5782	template<typename _Tp, typename _Compare>
5783	_GLIBCXX14_CONSTEXPR
5784	inline _Tp
5785	min(initializer_list<_Tp> __l, _Compare __comp)
5786	{
5787	__glibcxx_requires_irreflexive_pred(__l.begin(), __l.end(), __comp);
5788	return *_GLIBCXX_STD_A::__min_element(__l.begin(), __l.end(),
5789	__gnu_cxx::__ops::__iter_comp_iter(__comp));
5790	}
5791
5792	template<typename _Tp>
5793	_GLIBCXX14_CONSTEXPR
5794	inline _Tp
5795	max(initializer_list<_Tp> __l)
5796	{
5797	__glibcxx_requires_irreflexive(__l.begin(), __l.end());
5798	return *_GLIBCXX_STD_A::__max_element(__l.begin(), __l.end(),
5799	__gnu_cxx::__ops::__iter_less_iter());
5800	}
5801
5802	template<typename _Tp, typename _Compare>
5803	_GLIBCXX14_CONSTEXPR
5804	inline _Tp
5805	max(initializer_list<_Tp> __l, _Compare __comp)
5806	{
5807	__glibcxx_requires_irreflexive_pred(__l.begin(), __l.end(), __comp);
5808	return *_GLIBCXX_STD_A::__max_element(__l.begin(), __l.end(),
5809	__gnu_cxx::__ops::__iter_comp_iter(__comp));
5810	}
5811	#endif // C++11
5812
5813	#if __cplusplus >= 201402L
5814	/// Reservoir sampling algorithm.
5815	template<typename _InputIterator, typename _RandomAccessIterator,
5816	typename _Size, typename _UniformRandomBitGenerator>
5817	_RandomAccessIterator
5818	__sample(_InputIterator __first, _InputIterator __last, input_iterator_tag,
5819	_RandomAccessIterator __out, random_access_iterator_tag,
5820	_Size __n, _UniformRandomBitGenerator&& __g)
5821	{
5822	using __distrib_type = uniform_int_distribution<_Size>;
5823	using __param_type = typename __distrib_type::param_type;
5824	__distrib_type __d{};
5825	_Size __sample_sz = `0`;
5826	while (__first != __last && __sample_sz != __n)
5827	{
5828	__out[__sample_sz++] = *__first;
5829	++__first;
5830	}
5831	for (auto __pop_sz = __sample_sz; __first != __last;
5832	++__first, (void) ++__pop_sz)
5833	{
5834	const auto __k = __d(__g, __param_type{`0`, __pop_sz});
5835	if (__k < __n)
5836	__out[__k] = *__first;
5837	}
5838	return __out + __sample_sz;
5839	}
5840
5841	/// Selection sampling algorithm.
5842	template<typename _ForwardIterator, typename _OutputIterator, typename _Cat,
5843	typename _Size, typename _UniformRandomBitGenerator>
5844	_OutputIterator
5845	__sample(_ForwardIterator __first, _ForwardIterator __last,
5846	forward_iterator_tag,
5847	_OutputIterator __out, _Cat,
5848	_Size __n, _UniformRandomBitGenerator&& __g)
5849	{
5850	using __distrib_type = uniform_int_distribution<_Size>;
5851	using __param_type = typename __distrib_type::param_type;
5852	using _USize = make_unsigned_t<_Size>;
5853	using _Gen = remove_reference_t<_UniformRandomBitGenerator>;
5854	using __uc_type = common_type_t<typename _Gen::result_type, _USize>;
5855
5856	if (__first == __last)
5857	return __out;
5858
5859	__distrib_type __d{};
5860	_Size __unsampled_sz = std::distance(__first, __last);
5861	__n = std::min(__n, __unsampled_sz);
5862
5863	// If possible, we use __gen_two_uniform_ints to efficiently produce
5864	// two random numbers using a single distribution invocation:
5865
5866	const __uc_type __urngrange = __g.max() - __g.min();
5867	if (__urngrange / __uc_type(__unsampled_sz) >= __uc_type(__unsampled_sz))
5868	// I.e. (__urngrange >= __unsampled_sz __unsampled_sz) but without*
5869	// wrapping issues.
5870	{
5871	while (__n != `0` && __unsampled_sz >= `2`)
5872	{
5873	const pair<_Size, _Size> __p =
5874	__gen_two_uniform_ints(__unsampled_sz, __unsampled_sz - `1`, __g);
5875
5876	--__unsampled_sz;
5877	if (__p.first < __n)
5878	{
5879	__out++ = __first;
5880	--__n;
5881	}
5882
5883	++__first;
5884
5885	if (__n == `0`) break;
5886
5887	--__unsampled_sz;
5888	if (__p.second < __n)
5889	{
5890	__out++ = __first;
5891	--__n;
5892	}
5893
5894	++__first;
5895	}
5896	}
5897
5898	// The loop above is otherwise equivalent to this one-at-a-time version:
5899
5900	for (; __n != `0`; ++__first)
5901	if (__d(__g, __param_type{`0`, --__unsampled_sz}) < __n)
5902	{
5903	__out++ = __first;
5904	--__n;
5905	}
5906	return __out;
5907	}
5908
5909	#if __cplusplus > 201402L
5910	#define __cpp_lib_sample 201603L
5911	/// Take a random sample from a population.
5912	template<typename _PopulationIterator, typename _SampleIterator,
5913	typename _Distance, typename _UniformRandomBitGenerator>
5914	_SampleIterator
5915	sample(_PopulationIterator __first, _PopulationIterator __last,
5916	_SampleIterator __out, _Distance __n,
5917	_UniformRandomBitGenerator&& __g)
5918	{
5919	using __pop_cat = typename
5920	std::iterator_traits<_PopulationIterator>::iterator_category;
5921	using __samp_cat = typename
5922	std::iterator_traits<_SampleIterator>::iterator_category;
5923
5924	static_assert(
5925	__or_<is_convertible<__pop_cat, forward_iterator_tag>,
5926	is_convertible<__samp_cat, random_access_iterator_tag>>::value,
5927	"output range must use a RandomAccessIterator when input range"
5928	" does not meet the ForwardIterator requirements");
5929
5930	static_assert(is_integral<_Distance>::value,
5931	"sample size must be an integer type");
5932
5933	typename iterator_traits<_PopulationIterator>::difference_type __d = __n;
5934	return _GLIBCXX_STD_A::
5935	__sample(__first, __last, __pop_cat{}, __out, __samp_cat{}, __d,
5936	std::forward<_UniformRandomBitGenerator>(__g));
5937	}
5938	#endif // C++17
5939	#endif // C++14
5940
5941	_GLIBCXX_END_NAMESPACE_ALGO
5942	_GLIBCXX_END_NAMESPACE_VERSION
5943	} // namespace std
5944
5945	#endif /* _STL_ALGO_H */
5946

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