我最开始是这么写的

#include <stdio.h>

int a[55][55];

int f[55][55][55][55];

#define max(a, b) (a) > (b) ? (a) : (b)
int main()
{
    int m, n;
    scanf("%d%d", &m, &n);
    for (int i = 1; i <= m; i++)
    {
        for (int j = 1; j <= n; j++)
        {
            scanf("%d", &a[i][j]);
        }
    }
    for (int i = 1; i <= m; i++)
    {
        for (int j = 1; j <= n; j++)
        {
            for (int k = m; k > 0; k--)
            {
                for (int l = n; l > 0; l--)
                {
                    f[i][j][k][l] = a[i][j] + a[k][l];
                    int max1 = max(f[i - 1][j][k + 1][l], f[i][j - 1][k + 1][l]);
                    int max2 = max(f[i - 1][j][k][l + 1], f[i][j - 1][k][l + 1]);
                    f[i][j][k][l] += max(max1, max2);
                    if (i == k && j == l)
                        f[i][j][k][l] -= a[i][j];
                }
            }
        }
    }
    printf("%d\n", f[m][n][1][1]);
    return 0;
}

然后测试题目数据得35，目测就是重复了一个点 然后我测试了下面数据

3 3
0 1 0
0 0 0
0 0 0

然后跑出了2

然后将dp顺序都改成从左上往右下，然后就对了 请问各位巨巨这是为什么呢