【題解】ZeroJudge f162: 4. 獵人與斯芬克斯

#include <bits/stdc++.h>
using namespace std;

int K, n, m, tmp, ans;

int main(){
    cin >> K;
    cin >> n >> m;
    int a, pre[n+1][m+1] = {};
    for (int i = 1; i <= n; i++){
        for (int j = 1; j <= m; j++){
            cin >> a;
            pre[i][j] = pre[i-1][j]+pre[i][j-1]-pre[i-1][j-1]+a;
            //cout << pre[i][j] << " ";
            for (int k = 0; k < i; k++){
                for (int l = 0; l < j; l++){
                    tmp = pre[i][j]-pre[i][l]-pre[k][j]+pre[k][l];
                    //cout << k << " " << i << " " << l << " " << j << " " << tmp << "\n";
                    if (tmp <= K) ans = max(ans, tmp);
                }
            }
        }
        //cout << "\n";
    }
    cout << ans << "\n";
}