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

   1 // Copyright (C) 2001-2023 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 // { dg-add-options using-deprecated }
  19 // { dg-require-effective-target hosted }
  20
  21 // 25.2.11 random_shuffle()
  22
  23 #include <algorithm>
  24 #include <testsuite_hooks.h>
  25
  26 const int N = 200000;
  27 int A[N], s1[N];
  28
  29 #if _GLIBCXX_PARALLEL
  30 #define TAG , __gnu_parallel::sequential_tag()
  31 #else
  32 #define TAG
  33 #endif
  34
  35 void fill_ascending()
  36 {
  37   for (int i = 0; i < N; ++i)
  38     A[i] = i;
  39 }
  40
  41 void
  42 test01()
  43 {
  44   fill_ascending();
  45 #if _GLIBCXX_PARALLEL
  46   for (int num_threads = 1; num_threads <= 2; ++num_threads)
  47   {
  48     omp_set_num_threads(num_threads);
  49 #endif
  50     std::copy(A, A + N, s1);
  51     VERIFY(std::equal(s1, s1 + N, A TAG));
  52
  53     std::random_shuffle(s1, s1 + N);
  54     // the chance that random_shuffle leaves the order as is by coincidence
  55     // is negligible, so we expect it to be permuted
  56     VERIFY(!std::equal(s1, s1 + N, A TAG));
  57
  58     std::sort(s1, s1 + N TAG);
  59     VERIFY(std::equal(s1, s1 + N, A TAG));
  60 #if _GLIBCXX_PARALLEL
  61   }
  62 #endif
  63 }
  64
  65 int
  66 main()
  67 {
  68 #if _GLIBCXX_PARALLEL
  69   __gnu_parallel::_Settings gpms = __gnu_parallel::_Settings::get();
  70   gpms.algorithm_strategy = __gnu_parallel::force_parallel;
  71   __gnu_parallel::_Settings::set(gpms);
  72 #endif
  73   test01();
  74   return 0;
  75 }