k_largest_num_min_heap.cpp

/*
Given an array of N positive integers, print k largest elements from the array.  The output elements should be printed in decreasing order.

Input:
The first line of input contains an integer T denoting the number of test cases. The first line of each test case is N and k, N is the size of array and K is the largest elements to be returned. The second line of each test case contains N input C[i].

Output:
Print the k largest element in descending order.

Constraints:
1 ≤ T ≤ 100
1 ≤ N ≤ 100
K ≤ N
1 ≤ C[i] ≤ 1000

Example:
Input:
2
5 2
12 5 787 1 23
7 3
1 23 12 9 30 2 50

Output:
787 23
50 30 23

Explanation:
Testcase 1: 1st largest element in the array is 787 and second largest is 23.
Testcase 2: 3 Largest element in the array are 50, 30 and 23.
*/



#include<bits/stdc++.h>
using namespace std;

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    int t;
    cin>>t;
    while(t--){
        int n,k;
        cin>>n>>k;
        int a[n];
        for(int i=0;i<n;i++) cin>>a[i];

        // Implement min heap
        priority_queue<int, vector<int>, greater<int> > minh;
        for(int i=0;i<n;i++){
            minh.push(a[i]);
            if(minh.size()> k) minh.pop();
        }
        stack<int> s;
        while(!minh.empty()){
            s.push(minh.top());
            minh.pop();
        }
        // printing in descending order
        while(!s.empty()){
            cout<<s.top()<<" ";
            s.pop();
        }
        cout<<endl;
    }

return 0;
}