Priority queue of pairs in C++ (Ordered by first)

In C++, priority_queue implements heap. Below are some examples of creating priority queue of pair type.

Max Priority queue (Or Max heap) ordered by first element

// C++ program to create a priority queue of pairs.
// By default a max heap is created ordered
// by first element of pair.
#include <bits/stdc++.h>
using namespace std;

// Driver program to test methods of graph class
int main()
{
    // By default a max heap is created ordered
    // by first element of pair.
    priority_queue<pair<int, int> > pq;

    pq.push(make_pair(10, 200));
    pq.push(make_pair(20, 100));
    pq.push(make_pair(15, 400));

    pair<int, int> top = pq.top();
    cout << top.first << " " << top.second;
    return 0;
}

Output :

20 100


Min Priority queue (Or Min heap) ordered by first element

// C++ program to create a priority queue of pairs.
// We can create a min heap by passing adding two 
// parameters, vector and greater().
#include <bits/stdc++.h>
using namespace std;

typedef pair<int, int> pi;

// Driver program to test methods of graph class
int main()
{
    // By default a min heap is created ordered
    // by first element of pair.
    priority_queue<pi, vector<pi>, greater<pi> > pq;

    pq.push(make_pair(10, 200));
    pq.push(make_pair(20, 100));
    pq.push(make_pair(15, 400));

    pair<int, int> top = pq.top();
    cout << top.first << " " << top.second;
    return 0;
}

Output :

10 100


My Personal Notes arrow_drop_up

Check out this Author's contributed articles.

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.




Practice Tags :

Recommended Posts:



0 Average Difficulty : 0/5.0
No votes yet.






User Actions