题解 | 乘之

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

void solve(){
    int n, k;
    cin >> n >> k;
    vector<int> a(n);
    long long sum = 0;
    for(auto& num : a){
        cin >> num;
        sum += num;
    }
    cout << sum * k << endl;

}

int main() {
    int T;
    cin >> T;
    while(T--){
        solve();
    }

    return 0;
}
// 64 位输出请用 printf("%lld")