o57_oct_c2_pacman

#include <bits/stdc++.h>

using namespace std;
const int inf = 1e9;
const int N = 1e3 + 10;
int ar[N][N], dp[N][N][3];

int main(){

    int n, m;
    scanf("%d %d", &n, &m);

    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++){
            scanf("%d", &ar[i][j]);
        }
    }

    int ans = 0;
    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++){
            dp[i][j][0] = max({ i > 1 ? dp[i - 1][j][0] : 0 , j > 1 ? dp[i][j - 1][0] : 0 ,
                                i > 1 ? dp[i - 1][j][1] : 0 , j > 1 ? dp[i][j - 1][1] : 0 ,
                                i > 1 ? dp[i - 1][j][2] : 0 , j > 1 ? dp[i][j - 1][2] : 0 });
            dp[i][j][1] = ar[i][j] + max({ i > 1 ? dp[i - 1][j][0] : 0 , j > 1 ? dp[i][j - 1][0] : 0 });
            dp[i][j][2] = ar[i][j] + max({ i > 1 ? dp[i - 1][j][1] : 0 , j > 1 ? dp[i][j - 1][1] : 0});
        }
    }

    printf("%d", max({ dp[n][m][0] , dp[n][m][1] , dp[n][m][2] }));

    return 0;
}