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

   1 // Copyright (C) 2001-2018 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 // 25.2.11 random_shuffle()
  19
  20 #include <algorithm>
  21 #include <testsuite_hooks.h>
  22
  23 const int N = 200000;
  24 int A[N], s1[N];
  25
  26 #if _GLIBCXX_PARALLEL
  27 #define TAG , __gnu_parallel::sequential_tag()
  28 #else
  29 #define TAG
  30 #endif
  31
  32 void fill_ascending()
  33 {
  34   for (int i = 0; i < N; ++i)
  35     A[i] = i;
  36 }
  37
  38 void
  39 test01()
  40 {
  41   fill_ascending();
  42 #if _GLIBCXX_PARALLEL
  43   for (int num_threads = 1; num_threads <= 2; ++num_threads)
  44   {
  45     omp_set_num_threads(num_threads);
  46 #endif
  47     std::copy(A, A + N, s1);
  48     VERIFY(std::equal(s1, s1 + N, A TAG));
  49
  50     std::random_shuffle(s1, s1 + N);
  51     // the chance that random_shuffle leaves the order as is by coincidence
  52     // is negligible, so we expect it to be permuted
  53     VERIFY(!std::equal(s1, s1 + N, A TAG));
  54
  55     std::sort(s1, s1 + N TAG);
  56     VERIFY(std::equal(s1, s1 + N, A TAG));
  57 #if _GLIBCXX_PARALLEL
  58   }
  59 #endif
  60 }
  61
  62 int
  63 main()
  64 {
  65 #if _GLIBCXX_PARALLEL
  66   __gnu_parallel::_Settings gpms = __gnu_parallel::_Settings::get();
  67   gpms.algorithm_strategy = __gnu_parallel::force_parallel;
  68   __gnu_parallel::_Settings::set(gpms);
  69 #endif
  70   test01();
  71   return 0;
  72 }