python/TangDou/CSP-J/AcWingTraining/T6/126_ErWei.cpp

#include <bits/stdc++.h>
using namespace std;
const int INF = 0x3f3f3f3f;
const int N = 110;
int g[N][N];

int main() {
    int n;
    cin >> n;
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= n; j++) {
            cin >> g[i][j];
            // 累加出并记录同一列的前缀和
            g[i][j] += g[i - 1][j];
        }

    int res = -INF;

    // 枚举边界1，2
    for (int i = 1; i <= n; i++)       // 起始行
        for (int j = i; j <= n; j++) { // 终止行
            // 枚举边界p
            int last = 0;
            for (int k = 1; k <= n; k++) {
                last = max(last, 0) + g[j][k] - g[i - 1][k];
                res = max(res, last);
            }
        }

    cout << res << endl;
    return 0;
}