Codeforces Round #251 (Div. 2) B. Devu, the Dumb Guy

注意数据范围即可

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main(){
    long long n,x;
    cin >> n >> x;
    vector<long long> c(n);
    for(int i =  ; i < n; ++ i) cin >> c[i];
    sort(c.begin(),c.end());
    long long res = ;
    for(int i =  ; i <  n; ++ i){
        res +=c[i]*(x>  ? x--: );
    }
    cout<<res<<endl;
}