1420B - Rock and Lever - CodeForces Solution

// Online C++ compiler to run C++ program online
#include <bits/stdc++.h>
using namespace std; 

int main() {
    
    long long t;
    cin >> t;
    while(t--){
        long long n, k, mul=1, l=0, c=0;
        cin >> n;
        long long cnt=0;
        vector<long long> v;
        for(long long i=0;i<n;i++){
            long long x;
            cin >> x; 
            v.push_back(x); 
        }
        map<long long,long long > mpp;
        for(auto i:v)
        {
            long long z=log2(i)+1;
            mpp[z]++;
        
        } 
        
        for(auto i:mpp){
            if(i.second>1)
               cnt+=((i.second)*(i.second-1))/2; 
        }
        cout<<cnt<<endl;
    }
    return 0;
}