Noip 2008 传纸条

#include<cstdio>int f[55][55][55][55];int n,m,a[55][55];int max(int a,int b) {return a>b? a:b;}int main(){scanf("%d%d",&n,&m);for (int i=1;i<=n;i++)for (int j=1;j<=m;j++)scanf("%d",&a[i][j]);for (int i=1;i<=n;i++)for (int j=1;j<=m;j++)for (int k=1;k<=n;k++)for (int l=1;l<=m;l++){if ((i==k) && (j==l)) continue;f[i][j][k][l]=max(f[i-1][j][k-1][l],max(f[i-1][j][k][l-1],max(f[i][j-1][k-1][l],f[i][j-1][k][l-1])))+a[i][j]+a[k][l];}printf("%d",f[n][m-1][n-1][m]);return 0;}