[USACO5.3]巨大的牛棚Big Barn

 1 #include <cstdio>
 2 #include <iostream>
 3 #include <algorithm>
 4 using namespace std;
 5 int n,t,x,y,ans=-1<<29; 
 6 bool vis[1005][1005];
 7 int f[1005][1005];
 8 int main(){
 9     //freopen("2701.in","r",stdin);
10     //freopen("2701.out","w",stdout);
11     scanf("%d%d",&n,&t);
12     while(t--){
13         scanf("%d%d",&x,&y); 
14         vis[x][y]=true;
15     }
16     for(register int i=1;i<=n;i++){
17         for(register int j=1;j<=n;j++){
18             if(!vis[i][j])
19                 f[i][j]=min(f[i-1][j-1],min(f[i][j-1],f[i-1][j]))+1;
20             ans=max(ans,f[i][j]);
21         }
22     }
23     printf("%d\n",ans);
24     return 0;
25 }