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// Algorithm extensions -*- C++ -*-

// Copyright (C) 2001-2013 Free Software Foundation, Inc.

//

// This file is part of the GNU ISO C++ Library.  This library is free

// software; you can redistribute it and/or modify it under the

// terms of the GNU General Public License as published by the

// Free Software Foundation; either version 3, or (at your option)

// any later version.

// This library is distributed in the hope that it will be useful,

// but WITHOUT ANY WARRANTY; without even the implied warranty of

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

// GNU General Public License for more details.

// Under Section 7 of GPL version 3, you are granted additional

// permissions described in the GCC Runtime Library Exception, version

// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and

// a copy of the GCC Runtime Library Exception along with this program;

// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see

// .

/*

 *

 * Copyright (c) 1994

 * Hewlett-Packard Company

 *

 * Permission to use, copy, modify, distribute and sell this software

 * and its documentation for any purpose is hereby granted without fee,

 * provided that the above copyright notice appear in all copies and

 * that both that copyright notice and this permission notice appear

 * in supporting documentation.  Hewlett-Packard Company makes no

 * representations about the suitability of this software for any

 * purpose.  It is provided "as is" without express or implied warranty.

 *

 *

 * Copyright (c) 1996

 * Silicon Graphics Computer Systems, Inc.

 *

 * Permission to use, copy, modify, distribute and sell this software

 * and its documentation for any purpose is hereby granted without fee,

 * provided that the above copyright notice appear in all copies and

 * that both that copyright notice and this permission notice appear

 * in supporting documentation.  Silicon Graphics makes no

 * representations about the suitability of this software for any

 * purpose.  It is provided "as is" without express or implied warranty.

 */

/** @file ext/algorithm

 *  This file is a GNU extension to the Standard C++ Library (possibly

 *  containing extensions from the HP/SGI STL subset).

 */

#ifndef _EXT_ALGORITHM

#define _EXT_ALGORITHM 1

#pragma GCC system_header

#include 

namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)

{

_GLIBCXX_BEGIN_NAMESPACE_VERSION

  using std::ptrdiff_t;

  using std::min;

  using std::pair;

  using std::input_iterator_tag;

  using std::random_access_iterator_tag;

  using std::iterator_traits;

  //--------------------------------------------------

  // copy_n (not part of the C++ standard)

  template

    pair<_InputIterator, _OutputIterator>

    __copy_n(_InputIterator __first, _Size __count,

	     _OutputIterator __result,

	     input_iterator_tag)

    {

      for ( ; __count > 0; --__count)

	{

	  *__result = *__first;

	  ++__first;

	  ++__result;

	}

      return pair<_InputIterator, _OutputIterator>(__first, __result);

    }

  template

    inline pair<_RAIterator, _OutputIterator>

    __copy_n(_RAIterator __first, _Size __count,

	     _OutputIterator __result,

	     random_access_iterator_tag)

    {

      _RAIterator __last = __first + __count;

      return pair<_RAIterator, _OutputIterator>(__last, std::copy(__first,

								  __last,

								  __result));

    }

  /**

   *  @brief Copies the range [first,first+count) into [result,result+count).

   *  @param  __first  An input iterator.

   *  @param  __count  The number of elements to copy.

   *  @param  __result An output iterator.

   *  @return   A std::pair composed of first+count and result+count.

   *

   *  This is an SGI extension.

   *  This inline function will boil down to a call to @c memmove whenever

   *  possible.  Failing that, if random access iterators are passed, then the

   *  loop count will be known (and therefore a candidate for compiler

   *  optimizations such as unrolling).

   *  @ingroup SGIextensions

  */

  template

    inline pair<_InputIterator, _OutputIterator>

    copy_n(_InputIterator __first, _Size __count, _OutputIterator __result)

    {

      // concept requirements

      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)

      __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,

	    typename iterator_traits<_InputIterator>::value_type>)

      return __gnu_cxx::__copy_n(__first, __count, __result,

				 std::__iterator_category(__first));

    }

  template

    int

    __lexicographical_compare_3way(_InputIterator1 __first1,

				   _InputIterator1 __last1,

				   _InputIterator2 __first2,

				   _InputIterator2 __last2)

    {

      while (__first1 != __last1 && __first2 != __last2)

	{

	  if (*__first1 < *__first2)

	    return -1;

	  if (*__first2 < *__first1)

	    return 1;

	  ++__first1;

	  ++__first2;

	}

      if (__first2 == __last2)

	return !(__first1 == __last1);

      else

	return -1;

    }

  inline int

  __lexicographical_compare_3way(const unsigned char* __first1,

				 const unsigned char* __last1,

				 const unsigned char* __first2,

				 const unsigned char* __last2)

  {

    const ptrdiff_t __len1 = __last1 - __first1;

    const ptrdiff_t __len2 = __last2 - __first2;

    const int __result = __builtin_memcmp(__first1, __first2,

					  min(__len1, __len2));

    return __result != 0 ? __result

			 : (__len1 == __len2 ? 0 : (__len1 < __len2 ? -1 : 1));

  }

  inline int

  __lexicographical_compare_3way(const char* __first1, const char* __last1,

				 const char* __first2, const char* __last2)

  {

#if CHAR_MAX == SCHAR_MAX

    return __lexicographical_compare_3way((const signed char*) __first1,

					  (const signed char*) __last1,

					  (const signed char*) __first2,

					  (const signed char*) __last2);

#else

    return __lexicographical_compare_3way((const unsigned char*) __first1,

					  (const unsigned char*) __last1,

					  (const unsigned char*) __first2,

					  (const unsigned char*) __last2);

#endif

  }

  /**

   *  @brief @c memcmp on steroids.

   *  @param  __first1  An input iterator.

   *  @param  __last1   An input iterator.

   *  @param  __first2  An input iterator.

   *  @param  __last2   An input iterator.

   *  @return   An int, as with @c memcmp.

   *

   *  The return value will be less than zero if the first range is

   *  lexigraphically less than the second, greater than zero

   *  if the second range is lexigraphically less than the

   *  first, and zero otherwise.

   *  This is an SGI extension.

   *  @ingroup SGIextensions

  */

  template

    int

    lexicographical_compare_3way(_InputIterator1 __first1,

				 _InputIterator1 __last1,

				 _InputIterator2 __first2,

				 _InputIterator2 __last2)

    {

      // concept requirements

      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)

      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)

      __glibcxx_function_requires(_LessThanComparableConcept<

	    typename iterator_traits<_InputIterator1>::value_type>)

      __glibcxx_function_requires(_LessThanComparableConcept<

	    typename iterator_traits<_InputIterator2>::value_type>)

      __glibcxx_requires_valid_range(__first1, __last1);

      __glibcxx_requires_valid_range(__first2, __last2);

      return __lexicographical_compare_3way(__first1, __last1, __first2,

					    __last2);

    }

  // count and count_if: this version, whose return type is void, was present

  // in the HP STL, and is retained as an extension for backward compatibility.

  template

    void

    count(_InputIterator __first, _InputIterator __last,

	  const _Tp& __value,

	  _Size& __n)

    {

      // concept requirements

      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)

      __glibcxx_function_requires(_EqualityComparableConcept<

	    typename iterator_traits<_InputIterator>::value_type >)

      __glibcxx_function_requires(_EqualityComparableConcept<_Tp>)

      __glibcxx_requires_valid_range(__first, __last);

      for ( ; __first != __last; ++__first)

	if (*__first == __value)

	  ++__n;

    }

  template

    void

    count_if(_InputIterator __first, _InputIterator __last,

	     _Predicate __pred,

	     _Size& __n)

    {

      // concept requirements

      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)

      __glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,

	    typename iterator_traits<_InputIterator>::value_type>)

      __glibcxx_requires_valid_range(__first, __last);

      for ( ; __first != __last; ++__first)

	if (__pred(*__first))

	  ++__n;

    }

  // random_sample and random_sample_n (extensions, not part of the standard).

  /**

   *  This is an SGI extension.

   *  @ingroup SGIextensions

   *  @doctodo

  */

  template

	   typename _Distance>

    _OutputIterator

    random_sample_n(_ForwardIterator __first, _ForwardIterator __last,

                    _OutputIterator __out, const _Distance __n)

    {

      // concept requirements

      __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)

      __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,

		typename iterator_traits<_ForwardIterator>::value_type>)

      __glibcxx_requires_valid_range(__first, __last);

      _Distance __remaining = std::distance(__first, __last);

      _Distance __m = min(__n, __remaining);

      while (__m > 0)

	{

	  if ((std::rand() % __remaining) < __m)

	    {

	      *__out = *__first;

	      ++__out;

	      --__m;

	    }

	  --__remaining;

	  ++__first;

	}

      return __out;

    }

  /**

   *  This is an SGI extension.

   *  @ingroup SGIextensions

   *  @doctodo

  */

  template

	   typename _Distance, typename _RandomNumberGenerator>

    _OutputIterator

    random_sample_n(_ForwardIterator __first, _ForwardIterator __last,

                   _OutputIterator __out, const _Distance __n,

		   _RandomNumberGenerator& __rand)

    {

      // concept requirements

      __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)

      __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,

		typename iterator_traits<_ForwardIterator>::value_type>)

      __glibcxx_function_requires(_UnaryFunctionConcept<

		_RandomNumberGenerator, _Distance, _Distance>)

      __glibcxx_requires_valid_range(__first, __last);

      _Distance __remaining = std::distance(__first, __last);

      _Distance __m = min(__n, __remaining);

      while (__m > 0)

	{

	  if (__rand(__remaining) < __m)

	    {

	      *__out = *__first;

	      ++__out;

	      --__m;

	    }

	  --__remaining;

	  ++__first;

	}

      return __out;

    }

  template

	   typename _Distance>

    _RandomAccessIterator

    __random_sample(_InputIterator __first, _InputIterator __last,

		    _RandomAccessIterator __out,

		    const _Distance __n)

    {

      _Distance __m = 0;

      _Distance __t = __n;

      for ( ; __first != __last && __m < __n; ++__m, ++__first)

	__out[__m] = *__first;

      while (__first != __last)

	{

	  ++__t;

	  _Distance __M = std::rand() % (__t);

	  if (__M < __n)

	    __out[__M] = *__first;

	  ++__first;

	}

      return __out + __m;

    }

  template

	   typename _RandomNumberGenerator, typename _Distance>

    _RandomAccessIterator

    __random_sample(_InputIterator __first, _InputIterator __last,

		    _RandomAccessIterator __out,

		    _RandomNumberGenerator& __rand,

		    const _Distance __n)

    {

      // concept requirements

      __glibcxx_function_requires(_UnaryFunctionConcept<

	    _RandomNumberGenerator, _Distance, _Distance>)

      _Distance __m = 0;

      _Distance __t = __n;

      for ( ; __first != __last && __m < __n; ++__m, ++__first)

	__out[__m] = *__first;

      while (__first != __last)

	{

	  ++__t;

	  _Distance __M = __rand(__t);

	  if (__M < __n)

	    __out[__M] = *__first;

	  ++__first;

	}

      return __out + __m;

    }

  /**

   *  This is an SGI extension.

   *  @ingroup SGIextensions

   *  @doctodo

  */

  template

    inline _RandomAccessIterator

    random_sample(_InputIterator __first, _InputIterator __last,

		  _RandomAccessIterator __out_first,

		  _RandomAccessIterator __out_last)

    {

      // concept requirements

      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)

      __glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<

	    _RandomAccessIterator>)

      __glibcxx_requires_valid_range(__first, __last);

      __glibcxx_requires_valid_range(__out_first, __out_last);

      return __random_sample(__first, __last,

			     __out_first, __out_last - __out_first);

    }

  /**

   *  This is an SGI extension.

   *  @ingroup SGIextensions

   *  @doctodo

  */

  template

	   typename _RandomNumberGenerator>

    inline _RandomAccessIterator

    random_sample(_InputIterator __first, _InputIterator __last,

		  _RandomAccessIterator __out_first,

		  _RandomAccessIterator __out_last,

		  _RandomNumberGenerator& __rand)

    {

      // concept requirements

      __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)

      __glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<

	    _RandomAccessIterator>)

      __glibcxx_requires_valid_range(__first, __last);

      __glibcxx_requires_valid_range(__out_first, __out_last);

      return __random_sample(__first, __last,

			     __out_first, __rand,

			     __out_last - __out_first);

    }

#if __cplusplus >= 201103L

  using std::is_heap;

#else

  /**

   *  This is an SGI extension.

   *  @ingroup SGIextensions

   *  @doctodo

  */

  template

    inline bool

    is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)

    {

      // concept requirements

      __glibcxx_function_requires(_RandomAccessIteratorConcept<

				  _RandomAccessIterator>)

      __glibcxx_function_requires(_LessThanComparableConcept<

	    typename iterator_traits<_RandomAccessIterator>::value_type>)

      __glibcxx_requires_valid_range(__first, __last);

      return std::__is_heap(__first, __last - __first);

    }

  /**

   *  This is an SGI extension.

   *  @ingroup SGIextensions

   *  @doctodo

  */

  template

    inline bool

    is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last,

	    _StrictWeakOrdering __comp)

    {

      // concept requirements

      __glibcxx_function_requires(_RandomAccessIteratorConcept<

				  _RandomAccessIterator>)

      __glibcxx_function_requires(_BinaryPredicateConcept<_StrictWeakOrdering,

	    typename iterator_traits<_RandomAccessIterator>::value_type,

	    typename iterator_traits<_RandomAccessIterator>::value_type>)

      __glibcxx_requires_valid_range(__first, __last);

      return std::__is_heap(__first, __comp, __last - __first);

    }

#endif

#if __cplusplus >= 201103L

  using std::is_sorted;

#else

  // is_sorted, a predicated testing whether a range is sorted in

  // nondescending order.  This is an extension, not part of the C++

  // standard.

  /**

   *  This is an SGI extension.

   *  @ingroup SGIextensions

   *  @doctodo

  */

  template

    bool

    is_sorted(_ForwardIterator __first, _ForwardIterator __last)

    {

      // concept requirements

      __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)

      __glibcxx_function_requires(_LessThanComparableConcept<

	    typename iterator_traits<_ForwardIterator>::value_type>)

      __glibcxx_requires_valid_range(__first, __last);

      if (__first == __last)

	return true;

      _ForwardIterator __next = __first;

      for (++__next; __next != __last; __first = __next, ++__next)

	if (*__next < *__first)

	  return false;

      return true;

    }

  /**

   *  This is an SGI extension.

   *  @ingroup SGIextensions

   *  @doctodo

  */

  template

    bool

    is_sorted(_ForwardIterator __first, _ForwardIterator __last,

	      _StrictWeakOrdering __comp)

    {

      // concept requirements

      __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)

      __glibcxx_function_requires(_BinaryPredicateConcept<_StrictWeakOrdering,

	    typename iterator_traits<_ForwardIterator>::value_type,

	    typename iterator_traits<_ForwardIterator>::value_type>)

      __glibcxx_requires_valid_range(__first, __last);

      if (__first == __last)

	return true;

      _ForwardIterator __next = __first;

      for (++__next; __next != __last; __first = __next, ++__next)

	if (__comp(*__next, *__first))

	  return false;

      return true;

    }

#endif  // C++11

  /**

   *  @brief Find the median of three values.

   *  @param  __a  A value.

   *  @param  __b  A value.

   *  @param  __c  A value.

   *  @return One of @p a, @p b or @p c.

   *

   *  If @c {l,m,n} is some convolution of @p {a,b,c} such that @c l<=m<=n

   *  then the value returned will be @c m.

   *  This is an SGI extension.

   *  @ingroup SGIextensions

  */

  template

    const _Tp&

    __median(const _Tp& __a, const _Tp& __b, const _Tp& __c)

    {

      // concept requirements

      __glibcxx_function_requires(_LessThanComparableConcept<_Tp>)

      if (__a < __b)

	if (__b < __c)

	  return __b;

	else if (__a < __c)

	  return __c;

	else

	  return __a;

      else if (__a < __c)

	return __a;

      else if (__b < __c)

	return __c;

      else

	return __b;

    }

  /**

   *  @brief Find the median of three values using a predicate for comparison.

   *  @param  __a     A value.

   *  @param  __b     A value.

   *  @param  __c     A value.

   *  @param  __comp  A binary predicate.

   *  @return One of @p a, @p b or @p c.

   *

   *  If @c {l,m,n} is some convolution of @p {a,b,c} such that @p comp(l,m)

   *  and @p comp(m,n) are both true then the value returned will be @c m.

   *  This is an SGI extension.

   *  @ingroup SGIextensions

  */

  template

    const _Tp&

    __median(const _Tp& __a, const _Tp& __b, const _Tp& __c, _Compare __comp)

    {

      // concept requirements

      __glibcxx_function_requires(_BinaryFunctionConcept<_Compare, bool,

				                         _Tp, _Tp>)

      if (__comp(__a, __b))

	if (__comp(__b, __c))

	  return __b;

	else if (__comp(__a, __c))

	  return __c;

	else

	  return __a;

      else if (__comp(__a, __c))

	return __a;

      else if (__comp(__b, __c))

	return __c;

      else

	return __b;

    }

_GLIBCXX_END_NAMESPACE_VERSION

} // namespace

#endif /* _EXT_ALGORITHM */