stl priority queue code example

Example 1: priority queue cpp

// using GCC 10.2 (C++2a) compiler
#include <functional>
#include <queue>
#include <vector>
#include <iostream>
 
template<typename T> void print_queue(T& q) {
    while(!q.empty()) {
        std::cout << q.top() << " ";
        q.pop();
    }
    std::cout << '\n';
}
 
int main() {
    std::priority_queue<int> q;
 
    for(int n : {1,8,5,6,3,4,0,9,7,2})
        q.push(n);
 
    print_queue(q);
 
    std::priority_queue<int, std::vector<int>, std::greater<int> > q2;
 
    for(int n : {1,8,5,6,3,4,0,9,7,2})
        q2.push(n);
 
    print_queue(q2);
 
    // Using lambda to compare elements.
    auto cmp = [](int left, int right) { return (left ^ 1) < (right ^ 1); };
    std::priority_queue<int, std::vector<int>, decltype(cmp)> q3(cmp);
 
    for(int n : {1,8,5,6,3,4,0,9,7,2})
        q3.push(n);
 
    print_queue(q3);
 
}

Example 2: priority queue in c++

//Shubh'grepper
// Implementation of priority_queue in c++

//queue with elements in decreasing order
priority_queue<int> pq;

// queue with elements in increasing order  using compare function inside declaration
priority_queue <int, vector<int>, greater<int> > pq;

//priority_queue of type pair<int, int>
#define pp pair<int, int>
priority_queue <pp, vector<pp>, greater<pp> > pq;

Example 3: priority queue stl

#include<iostream>
#include<queue>
#include<algorithm>

using namespace std;

int main()
{
    priority_queue<int>pq;
    int n=5;
    while(n--)
    {
        int val;
        cout<<"enter the value you want to insert:"<<endl;
        cin>>val;
        pq.push(val);
    }
    priority_queue<int>p;
    p.push(100);
    p.push(1000);
    p.push(3000);
    p.push(5000);
    pq.swap(p);
    while(!pq.empty())
    {
        cout<<pq.top()<<" ";
        pq.pop();
    }
    return 0;
}