Not clear of concept

Akshita99 · June 2, 2020, 5:34am

i am using priority queue of pair in which 1st number is value and 2nd number is its frequency, and don’t know how to update frequency of a number in the priority queue. please tell

mayankA47 · June 2, 2020, 5:57am

@Akshita99 because of this problem, priority queue is not fair data structure to tackle this problem. Try thinking of some algo using set/hashmap.

Akshita99 · June 2, 2020, 8:52am

sir i even tried using maps, but there i was not able to include my own comparator which can store them based on both first and second values

mayankA47 · June 2, 2020, 9:16am

github.com

mayankA47/Lets_Code/blob/mayankA47-patch-1/top_K_frequent_elements_in_running_stream.cpp

#include<bits/stdc++.h>
using namespace std;
struct mycmp
    {
      bool operator()(pair<int,int> a,pair<int,int> b) const{
        if(a.first!=b.first)
			return a.first>b.first;
		return a.second<b.second;
      }
      
    };
int main() {
	int t;
	cin>>t;
	while(t--){
		int n,k;
		cin>>n>>k;
		set<pair<int,int>,mycmp> s;
		map<int,int> m;
		for(int i=0;i<n;i++){

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you can refer to my code,I did it using set(to maintain required order) and map(to keep frequency)