libstdc++-v3/testsuite/25_algorithms/nth_element/random_test.cc

   1 // Copyright (C) 2013-2025 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 // { dg-options "-DSIMULATOR_TEST" { target simulator } }
  19 // { dg-do run { target c++11 } }
  20 // { dg-require-cstdint "" }
  21
  22 // 25.4.2 [lib.alg.nth.element]
  23
  24 #include <algorithm>
  25 #include <random>
  26 #include <testsuite_hooks.h>
  27 #include <testsuite_iterators.h>
  28 #include <testsuite_containergen.h>
  29
  30 using __gnu_test::test_container;
  31 using __gnu_test::random_access_iterator_wrapper;
  32
  33 typedef test_container<int, random_access_iterator_wrapper> Container;
  34
  35 struct testNthElement
  36 {
  37   template<typename Container, typename RandomGen>
  38   void operator()(Container con, RandomGen& rg)
  39   {
  40     const int size = con.end() - con.begin();
  41     auto dist = std::uniform_int_distribution<>(0, size);
  42     const int element = dist(rg);
  43
  44     std::nth_element(con.begin(), con.begin() + element, con.end());
  45
  46     if (element < size)
  47       {
  48         for (int i = 0; i < element; ++i)
  49           VERIFY( con.val(i) <= con.val(element) );
  50
  51         for (int i = element + 1; i < size; ++i)
  52           VERIFY( con.val(i) >= con.val(element) );
  53       }
  54   }
  55 };
  56
  57 int
  58 main()
  59 {
  60   __gnu_test::test_containers<Container>(testNthElement());
  61 }