洛谷 P1736 创意吃鱼法

#include<cstdio>
#include<iostream>
#include<cstring>
using namespace std;

int ans,m,n,f[2509][2509],dp[2509][2509],a[2509][2509],h[2509][2509],s[2509][2509];
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]);
if(!a[i][j])
{
h[i][j]=h[i][j-1]+(a[i][j]^1);
s[i][j]=s[i-1][j]+(a[i][j]^1);
}
if(a[i][j])f[i][j]=(min(f[i-1][j-1],min(s[i-1][j],h[i][j-1]))+1)*a[i][j];
}

memset(h,0,sizeof h);
memset(s,0,sizeof s);
for(int i=1;i<=n;i++)
for(int j=m;j>=1;j--)
{
if(!a[i][j])
{
h[i][j]=h[i][j+1]+(a[i][j]^1);
s[i][j]=s[i-1][j]+(a[i][j]^1);
}
dp[i][j]=(min(dp[i-1][j+1],min(s[i-1][j],h[i][j+1]))+1)*a[i][j];
}

for(int i=1;i<=n;i++)
for(int j=1;j<=m;j++)

ans=max(ans,max(dp[i][j],f[i][j]));
printf("%d",ans);
}