libstdc++-v3/testsuite/ext/pb_ds/example/tree_order_statistics.cc

// -*- C++ -*-

// Copyright (C) 2005-2021 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.

// You should have received a copy of the GNU General Public License
// along with this library; see the file COPYING3.  If not see
// <http://www.gnu.org/licenses/>.


// Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.

// Permission to use, copy, modify, sell, and distribute this software
// is hereby granted without fee, provided that the above copyright
// notice appears in all copies, and that both that copyright notice
// and this permission notice appear in supporting documentation. None
// of the above authors, nor IBM Haifa Research Laboratories, make any
// representation about the suitability of this software for any
// purpose. It is provided "as is" without express or implied
// warranty.

/**
 * @file tree_order_statistics_example.cpp
 * An example showing how to use functors for order-statistics
 *    in tree-based containers.
 */

/**
 * In some cases tree structure can be used for various purposes asides
 *    from storing entries by key order.
 *    This example shows how a tree-based container can be used for
 *    order-statistics, i.e., for determining the order of each key
 *     in the (ordered) sequence of keys stored within the container object.
 */

#include <cassert>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

// A red-black tree table storing ints and their order
// statistics. Note that since the tree uses
// tree_order_statistics_node_update as its update policy, then it
// includes its methods by_order and order_of_key.
typedef
tree<
  int,
  null_type,
  less<int>,
  rb_tree_tag,
  // This policy updates nodes' metadata for order statistics.
  tree_order_statistics_node_update>
set_t;

int main()
{
  // Insert some entries into s.
  set_t s;
  s.insert(12);
  s.insert(505);
  s.insert(30);
  s.insert(1000);
  s.insert(10000);
  s.insert(100);

  // The order of the keys should be: 12, 30, 100, 505, 1000, 10000.
  assert(*s.find_by_order(0) == 12);
  assert(*s.find_by_order(1) == 30);
  assert(*s.find_by_order(2) == 100);
  assert(*s.find_by_order(3) == 505);
  assert(*s.find_by_order(4) == 1000);
  assert(*s.find_by_order(5) == 10000);
  assert(s.find_by_order(6) == s.end());

  // The order of the keys should be: 12, 30, 100, 505, 1000, 10000.
  assert(s.order_of_key(10) == 0);
  assert(s.order_of_key(12) == 0);
  assert(s.order_of_key(15) == 1);
  assert(s.order_of_key(30) == 1);
  assert(s.order_of_key(99) == 2);
  assert(s.order_of_key(100) == 2);
  assert(s.order_of_key(505) == 3);
  assert(s.order_of_key(1000) == 4);
  assert(s.order_of_key(10000) == 5);
  assert(s.order_of_key(9999999) == 6);

  // Erase an entry.
  s.erase(30);

  // The order of the keys should be: 12, 100, 505, 1000, 10000.
  assert(*s.find_by_order(0) == 12);
  assert(*s.find_by_order(1) == 100);
  assert(*s.find_by_order(2) == 505);
  assert(*s.find_by_order(3) == 1000);
  assert(*s.find_by_order(4) == 10000);
  assert(s.find_by_order(5) == s.end());

  // The order of the keys should be: 12, 100, 505, 1000, 10000.
  assert(s.order_of_key(10) == 0);
  assert(s.order_of_key(12) == 0);
  assert(s.order_of_key(100) == 1);
  assert(s.order_of_key(505) == 2);
  assert(s.order_of_key(707) == 3);
  assert(s.order_of_key(1000) == 3);
  assert(s.order_of_key(1001) == 4);
  assert(s.order_of_key(10000) == 4);
  assert(s.order_of_key(100000) == 5);
  assert(s.order_of_key(9999999) == 5);

  return 0;
}