libstdc++-v3/testsuite/25_algorithms/next_permutation/1.cc

   1 // Copyright (C) 2005-2025 Free Software Foundation, Inc.
   2 //
   3 // This file is part of the GNU ISO C++ Library.  This library is free
   4 // software; you can redistribute it and/or modify it under the
   5 // terms of the GNU General Public License as published by the
   6 // Free Software Foundation; either version 3, or (at your option)
   7 // any later version.
   8
   9 // This library is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13
  14 // You should have received a copy of the GNU General Public License along
  15 // with this library; see the file COPYING3.  If not see
  16 // <http://www.gnu.org/licenses/>.
  17
  18 // 25.3.9 [lib.alg.permutation.generators]
  19
  20 #include <algorithm>
  21 #include <testsuite_hooks.h>
  22 #include <testsuite_iterators.h>
  23
  24 using __gnu_test::test_container;
  25 using __gnu_test::bidirectional_iterator_wrapper;
  26 using std::next_permutation;
  27
  28 typedef test_container<int, bidirectional_iterator_wrapper> Container;
  29
  30 void
  31 test1()
  32 {
  33   // Note: The standard is unclear on what should happen in this case.
  34   // This seems the only really sensible behaviour, and what is done.
  35   int array[] = {0};
  36   Container con(array, array);
  37   VERIFY(!next_permutation(con.begin(), con.end()));
  38 }
  39
  40 void
  41 test2()
  42 {
  43   int array[] = {0};
  44   Container con(array, array + 1);
  45   VERIFY(!next_permutation(con.begin(), con.end()));
  46 }
  47
  48 void
  49 test3()
  50 {
  51   int array[] = {0, 3};
  52   Container con(array, array + 2);
  53   VERIFY(next_permutation(con.begin(), con.end()));
  54   VERIFY(array[0] == 3 && array[1] == 0);
  55   VERIFY(!next_permutation(con.begin(), con.end()));
  56   VERIFY(array[0] == 0 && array[1] == 3);
  57 }
  58
  59 void
  60 test4()
  61 {
  62   int array[6] = {0, 1, 2, 3, 4, 5};
  63   Container con(array, array + 6);
  64   for(int i = 0 ; i < 719; ++i)
  65     {
  66       int temp_array[6];
  67       std::copy(array, array + 6, temp_array);
  68       VERIFY(next_permutation(array, array + 6));
  69       VERIFY(std::lexicographical_compare(temp_array, temp_array + 6,
  70                                           array, array + 6));
  71     }
  72   VERIFY(!next_permutation(array,array + 6));
  73   for(int i = 0; i < 6; ++i)
  74     VERIFY(array[i] == i);
  75 }
  76
  77 int main()
  78 {
  79   test1();
  80   test2();
  81   test3();
  82   test4();
  83 }