priority queue stl

1/* A priority queue maintains a set of elements. The supported operations are
2insertion and, depending on the type of the queue, retrieval and removal 
3of either the minimum or maximum element. Insertion and removal take 
4O(logn) time, and retrieval takes O(1) time. */
5priority_queue<int> q;
6q.push(3); // 3
7q.push(5); // 3 5
8q.push(7); // 3 5 7
9q.push(2); // 2 3 5 7
10cout << q.top() << "\n"; // 7
11q.pop();
12cout << q.top() << "\n"; // 5
13q.pop();
14q.push(6);
15cout << q.top() << "\n"; // 6
16q.pop();

1// using GCC 10.2 (C++2a) compiler
2#include <functional>
3#include <queue>
4#include <vector>
5#include <iostream>
6 
7template<typename T> void print_queue(T& q) {
8    while(!q.empty()) {
9        std::cout << q.top() << " ";
10        q.pop();
11    }
12    std::cout << '\n';
13}
14 
15int main() {
16    std::priority_queue<int> q;
17 
18    for(int n : {1,8,5,6,3,4,0,9,7,2})
19        q.push(n);
20 
21    print_queue(q);
22 
23    std::priority_queue<int, std::vector<int>, std::greater<int> > q2;
24 
25    for(int n : {1,8,5,6,3,4,0,9,7,2})
26        q2.push(n);
27 
28    print_queue(q2);
29 
30    // Using lambda to compare elements.
31    auto cmp = [](int left, int right) { return (left ^ 1) < (right ^ 1); };
32    std::priority_queue<int, std::vector<int>, decltype(cmp)> q3(cmp);
33 
34    for(int n : {1,8,5,6,3,4,0,9,7,2})
35        q3.push(n);
36 
37    print_queue(q3);
38 
39}
40

1//Shubh'grepper
2// Implementation of priority_queue in c++
3
4//queue with elements in decreasing order
5priority_queue<int> pq;
6
7// queue with elements in increasing order  using compare function inside declaration
8priority_queue <int, vector<int>, greater<int> > pq;
9
10//priority_queue of type pair<int, int>
11#define pp pair<int, int>
12priority_queue <pp, vector<pp>, greater<pp> > pq;
13

1std::priority_queue<int, std::vector<int>, std::greater<int>>

1#include<iostream>
2#include<queue>
3#include<algorithm>
4
5using namespace std;
6
7int main()
8{
9    priority_queue<int>pq;
10    int n=5;
11    while(n--)
12    {
13        int val;
14        cout<<"enter the value you want to insert:"<<endl;
15        cin>>val;
16        pq.push(val);
17    }
18    priority_queue<int>p;
19    p.push(100);
20    p.push(1000);
21    p.push(3000);
22    p.push(5000);
23    pq.swap(p);
24    while(!pq.empty())
25    {
26        cout<<pq.top()<<" ";
27        pq.pop();
28    }
29    return 0;
30}
31

1function PriorityQueue() {
2  this.collection = [];
3  this.printCollection = function () {
4    console.log(this.collection);
5  };
6  // Only change code below this line
7  this.enqueue = function (newitem) {
8    if (this.isEmpty()) {
9      return this.collection.push(newitem);
10    }
11
12    this.collection = this.collection.reverse();
13    var found_index = this.collection.findIndex(function (item) {
14      return newitem[1] >= item[1];
15    });
16    if (found_index === -1) {
17      this.collection.push(newitem);
18    } else {
19      this.collection.splice(found_index, 0, newitem);
20    }
21    this.collection = this.collection.reverse();
22  };
23  this.dequeue = function () {
24    if (!this.isEmpty()) {
25      return this.collection.shift()[0];
26    } else {
27      return "The queue is empty.";
28    }
29  };
30  this.size = function () {
31    return this.collection.length;
32  };
33  this.front = function () {
34    return this.collection[0][0];
35  };
36  this.isEmpty = function () {
37    return this.size() > 0 ? false : true;
38  };
39  // Only change code above this line
40}
41