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// Copyright (C) 2005 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 2, 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.

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

// with this library; see the file COPYING.  If not, write to the Free

// Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,

// USA.

// 25.3.9 [lib.alg.permutation.generators]

#include <algorithm>

#include <testsuite_hooks.h>

#include <testsuite_iterators.h>

using __gnu_test::test_container;

using __gnu_test::bidirectional_iterator_wrapper;

using std::prev_permutation;

typedef test_container<int, bidirectional_iterator_wrapper> Container;

void

test1()

{

  // Note: The standard is unclear on what should happen in this case.

  // This seems the only really sensible behaviour, and what is done.

  int array[] = {0};

  Container con(array, array);

  VERIFY(!prev_permutation(con.begin(), con.end()));

}

void

test2()

{

  int array[] = {0};

  Container con(array, array + 1);

  VERIFY(!prev_permutation(con.begin(), con.end()));

}

void

test3()

{

  int array[] = {3, 0};

  Container con(array, array + 2);

  VERIFY(prev_permutation(con.begin(), con.end()));

  VERIFY(array[0] == 0 && array[1] == 3);

  VERIFY(!prev_permutation(con.begin(), con.end()));

  VERIFY(array[0] == 3 && array[1] == 0);

}

void

test4()

{

  int array[6] = {5, 4, 3, 2, 1, 0};

  Container con(array, array + 6);

  for(int i = 0 ; i < 719; ++i)

    {

      int temp_array[6];

      std::copy(array, array + 6, temp_array);

      VERIFY(prev_permutation(array, array + 6));

      VERIFY(std::lexicographical_compare(array, array + 6,

                                          temp_array, temp_array + 6));

    }

  VERIFY(!prev_permutation(array,array + 6));

  for(int i = 0; i < 6; ++i)

    VERIFY(array[i] == 5 - i);

}

int main()

{

  test1();

  test2();

  test3();

  test4();

}