题解 | 乘之

#include <bits/stdc++.h>
using namespace std;
using ll=long long;
const int N=1e5+9;
ll k,T,n,a,ans;

int main() {
    cin>>T;
    while(T--) {
        ans=0;
        cin>>n>>k;
        for(int i=1;i<=n;i++) {
            cin>>a;ans+=a;
        }
        ans*=k;
        cout<<ans<<endl;
    }
    
}