examples/manual/priority_queue.cpp

/**************************************************************************
 *
 * p_queue.cpp - Example program of a priority queue.
 *
 * $Id$
 *
 ***************************************************************************
 *
 * Copyright (c) 1994-2005 Quovadx,  Inc., acting through its  Rogue Wave
 * Software division. Licensed under the Apache License, Version 2.0 (the
 * "License");  you may  not use this file except  in compliance with the
 * License.    You    may   obtain   a   copy   of    the   License    at
 * http://www.apache.org/licenses/LICENSE-2.0.    Unless   required    by
 * applicable law  or agreed to  in writing,  software  distributed under
 * the License is distributed on an "AS IS" BASIS,  WITHOUT WARRANTIES OR
 * CONDITIONS OF  ANY KIND, either  express or implied.  See  the License
 * for the specific language governing permissions  and limitations under
 * the License.
 * 
 **************************************************************************/
 
#include <deque>      // for deque
#include <iostream>   // for cout, endl
#include <queue>      // for priority_queue
#include <string>     // for string
#include <vector>     // for vector

#include <examples.h>


int main ()
{
    // Make a priority queue of int  using a vector container.
    std::priority_queue<int,
                        std::vector<int, std::allocator<int> >,
                        std::less<int> > pq;
    // Push a couple of values.
    pq.push (1);
    pq.push (2);

    // Pop a couple of values and examine the ends.
    std::cout << pq.top () << std::endl;
    pq.pop ();
    std::cout << pq.top () << std::endl;
    pq.pop ();

    // Make a priority queue of strings.
    std::priority_queue<std::string,
                        std::deque<std::string, std::allocator<std::string> >,
                        std::less<std::string> > pqs;

    // Push on a few strings then pop them back off.
    for (int i = 0; i < 10; i++) {
        pqs.push (std::string (i + 1, 'a'));
        std::cout << pqs.top () << std::endl;
    }

    for (int j = 0; j < 10; j++) {
        std::cout << pqs.top () << std::endl;
        pqs.pop ();
    }

    // Make a priority queue of strings using greater.
    std::priority_queue<std::string,
                        std::deque<std::string,
                                   std::allocator<std::string> >, 
                        std::greater<std::string> > pgqs;

    // Push on a few strings then pop them back off.
    for (int k = 0; k < 10; k++)  {
        pgqs.push (std::string (k + 1, 'a'));
        std::cout << pgqs.top () << std::endl;
    }

    for (int m = 0; m < 10; m++) {
        std::cout << pgqs.top () << std::endl;
        pgqs.pop ();
    }

    return 0;
}