Luogu 1006 Passing note

The question orz in multidimensional dynamic programming

Simplify the problem to pass two strips in one direction so use a four-dimensional array.

State transition equation:

\(f[i][j][k][l]=max(f[i-1][j][k-1][l],f[i][j-1][k-1][l],f[i-1][j][k][l-1],f[i][j-1][k][l-1])+map[i][j]+map[k][l]\)

#include<iostream>
#include<cstdio>
using namespace std;
int m,n,x,y,val,f[51][51][51][51],map[51][51];
int main(){
    scanf("%d%d",&m,&n);
    for(int i=1;i<=m;i++)
        for(int j=1;j<=n;j++)
            scanf("%d",&map[i][j]);
    for(int i=1;i<=m;i++)
        for(int j=1;j<=n;j++)
            for(int k=1;k<=m;k++)
                for(int l=1;l<=n;l++){
                    f[i][j][k][l]=max(f[i-1][j][k-1][l],max(f[i][j-1][k-1][l],max(f[i-1][j][k][l-1],f[i][j-1][k][l-1])))+map[i][j]+map[k][l];
                    if(i==k&&j==l)f[i][j][k][l]-=map[i][j];
                }
    printf("%d\n",f[m][n][m][n]);
    return 0;
}