#include ＜set＞

C++ 标准库中的 <set> 是一个关联容器，它存储了一组唯一的元素，并按照一定的顺序进行排序。

// <set> -*- C++ -*-

// Copyright (C) 2001-2020 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 3, 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.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

/*
 *
 * Copyright (c) 1994
 * Hewlett-Packard Company
 *
 * Permission to use, copy, modify, distribute and sell this software
 * and its documentation for any purpose is hereby granted without fee,
 * provided that the above copyright notice appear in all copies and
 * that both that copyright notice and this permission notice appear
 * in supporting documentation.  Hewlett-Packard Company makes no
 * representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied warranty.
 *
 *
 * Copyright (c) 1996,1997
 * Silicon Graphics Computer Systems, Inc.
 *
 * Permission to use, copy, modify, distribute and sell this software
 * and its documentation for any purpose is hereby granted without fee,
 * provided that the above copyright notice appear in all copies and
 * that both that copyright notice and this permission notice appear
 * in supporting documentation.  Silicon Graphics makes no
 * representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied warranty.
 */

/** @file include/set
 *  This is a Standard C++ Library header.
 */

#ifndef _GLIBCXX_SET
#define _GLIBCXX_SET 1

#pragma GCC system_header

#include <bits/stl_tree.h>
#include <bits/stl_set.h>
#include <bits/stl_multiset.h>
#include <bits/range_access.h>
#include <bits/erase_if.h>

#ifdef _GLIBCXX_DEBUG
# include <debug/set>
#endif

#if __cplusplus >= 201703L
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
  namespace pmr
  {
    template<typename _Tp> class polymorphic_allocator;
    template<typename _Key, typename _Cmp = std::less<_Key>>
      using set = std::set<_Key, _Cmp, polymorphic_allocator<_Key>>;
    template<typename _Key, typename _Cmp = std::less<_Key>>
      using multiset = std::multiset<_Key, _Cmp, polymorphic_allocator<_Key>>;
  } // namespace pmr
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
#endif // C++17

#if __cplusplus > 201703L
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
  template<typename _Key, typename _Compare, typename _Alloc,
	   typename _Predicate>
    inline typename set<_Key, _Compare, _Alloc>::size_type
    erase_if(set<_Key, _Compare, _Alloc>& __cont, _Predicate __pred)
    { return __detail::__erase_nodes_if(__cont, __pred); }

  template<typename _Key, typename _Compare, typename _Alloc,
	   typename _Predicate>
    inline typename multiset<_Key, _Compare, _Alloc>::size_type
    erase_if(multiset<_Key, _Compare, _Alloc>& __cont, _Predicate __pred)
    { return __detail::__erase_nodes_if(__cont, __pred); }
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
#endif // C++20

#endif /* _GLIBCXX_SET */

• insert(元素): 插入一个元素。
• erase(元素): 删除一个元素。
• find(元素): 查找一个元素。
• size(): 返回容器中元素的数量。
• empty(): 检查容器是否为空。