K Most Frequent Elements

// problem url: https://www.codingninjas.com/codestudio/problems/k-most-frequent-elements_3167808?topList=striver-sde-sheet-problems&utm_source=striver&utm_medium=website&leftPanelTab=0
// mode: Medium
// Heap

#include <bits/stdc++.h>
vector<int> KMostFrequent(int n, int k, vector<int> &arr){
    unordered_map<int, int> cntOfEle;
    for(int num: arr)
        ++cntOfEle[num];
    
    priority_queue<int, vector<vector<int>>> orderByCnt;
    for(auto &it: cntOfEle)
        orderByCnt.push({it.second, it.first});
    
    vector<int> ans;
    while(orderByCnt.size() && k--){
        ans.push_back(orderByCnt.top()[1]);
        orderByCnt.pop();
    }
    
    stable_sort(ans.begin(), ans.end());
    return ans;
}