f[i][j][k][l]=max(max(f[i−1][j][k][l],f[i][j−1][k][l])+a[i][j],max(f[i][j][k−1][l],f[i][j][k][l−1])+a[k][l])f[i][j][k][l]=\max(\max(f[i-1][j][k][l],f[i][j-1][k][l])+a[i][j],\max(f[i][j][k-1][l],f[i][j][k][l-1])+a[k][l])f[i][j][k][l]=max(max(f[i−1][j][k][l],f[i][j−1][k][l])+a[i][j],max(f[i][j][k−1][l],f[i][j][k][l−1])+a[k][l])
这个状态转移方程可以吗
