这暴力直接过了!!!

代码如下：

#include <bits/stdc++.h>
using namespace std;
int c[1001][1001], s[1001][1001];

int main() {
    int n;
    cin >> n;
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= n; j++) {
            cin >> c[i][j];
            s[i][j] += s[i - 1][j] + s[i][j - 1] + c[i][j] - s[i - 1][j - 1];
        }
    }
    int ans = -2147483647;
    for (int x = 1; x <= n; ++x) {
        for (int y = 1; y <= n; ++y) {
            for (int x2 = x + 1; x2 <= n; ++x2) {
                for (int y2 = y + 1; y2 <= n; ++y2) {
                    ans = max(s[x2][y2] - s[x - 1][y2] - s[x2][y - 1] + s[x - 1][y - 1], ans);
                }
            }
        }
    }
    cout << ans;
    return 0;
}

只用了前缀和,其他什么也没用！