This is my solution for the Codechef problem https://www.codechef.com/problems/ANUBTG

minimum_bill.cpp

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int main() {
	int t;
	cin >> t;
	while( t-- ) {
	    int n;
	    cin >> n;
	    vector<int> prices(n);
	    int i;
	    for(i = 0; i < n; i++)
	    {
	        cin >> prices[i];
	    }
	    sort( prices.begin(), prices.end(), greater<int>());
	    int amt = 0;
	    for(i = 0; i <= n-2; i+=4)
	    {
	        amt += prices[i]+prices[i+1];
	    }
	    if(i == n-1)
	        amt += prices[n-1];
	    cout << amt << endl;
	}
	return 0;
}