FUNKVAL - SLOW

#include <bits/stdc++.h>
#define check(N, A, B) assert((N) >= (A) && (N) <= (B))
using namespace std;
const int maxn = 30;
typedef long long ll;
int a[maxn][maxn];
int floor(int x){
    int l = 0, r = x;
    while(l < r){
        int m = l+(r-l)/2;
        if(m*m <= x) l = m+1;
        else r = m;
    }
    if(l*l > x) l--;
    return l;
}
int main(){
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    int n, k; cin >> n;
    check(n,1,25);
    for(int i=0;i<n;i++)
        for(int j=0;j<n;j++){
            cin >> a[i][j]; check(a[i][j],0,1e6);
        }
    for(int i=0;i<n;i++){
        assert(a[i][i] == 0);
        for(int j=0;j<n;j++)
            assert(a[i][j] == a[j][i]);
    }

    ll ans = 0;
    for(int i=0;i<(1<<n);i++){
        ll cur = 0;
        for(int j=0;j<n;j++)
            if(i&(1<<j)) for(int k=0;k<j;k++)
                if(i&(1<<k)) cur += a[j][k];
        // cout << i << ": " << cur << endl;
        ans += cur * floor(__builtin_popcount(i));
    }
    cout << ans << "\n";
}