题目描述

#include <iostream>
using namespace std;

const int N = 100 + 1;
int cnt[N];

int main(){
    int T; cin >> T;
    while(T--){
        int n,d; cin >> n >> d;
        for(int i = 1; i <= n; i++) cin >> cnt[i];
        int ans = cnt[1];
        for(int i = 2; i <= n; i++){
           int x = cnt[i];
           while((i-1)*x > d) x--;
           d-=(i-1)*x;
           ans += x;
        }
        cout << ans << endl;

    }



    return 0;
}