Counting Subsets CPH - page 115

#include <bits/stdc++.h>

using namespace std;

int main() {
    int N;
    cin >> N;
    vector < int > values(1 << N);
    for(int& x : values)
        cin >> x;
    vector < int > sum(1 << N);
    for(int i = 0; i < (1 << N); ++i)
        sum[i] = values[i];
    for(int k = 0; k < N; ++k)
        for(int s = 0; s < (1 << N); ++s)
            if(s & (1 << k))
                sum[s] += sum[s ^ (1 << k)];
    cout << sum[(1 << N) - 1];
}