ok啊干翻cpu了好吧

#include <iostream>
#include <algorithm>
using namespace std;
const int MAXN = 55;
int m, n, a[MAXN][MAXN], dp[MAXN][MAXN][MAXN];

int main() {
    cin >> m >> n;
    for (int i = 1; i <= m; i++)
        for (int j = 1; j <= n; j++)
            cin >> a[i][j];
    for (int i = 1; i <= m; i++)
        for (int j = 1; j <= n; j++)
            for (int k = 1; k <= m; k++) {
                int l = i + j - k;
                if (l >= 1 && l <= n) {
                    int temp = max(max(dp[i - 1][j][k - 1], dp[i - 1][j][k]), max(dp[i][j - 1][k - 1], dp[i][j - 1][k]));
                    dp[i][j][k] = temp + a[i][j];
                    if (i != k) dp[i][j][k] += a[k][l];
                }
            }
    cout << dp[m][n][m] << endl;
    return 0;
}