tyvj1189 盖房子

#include<iostream>
#include<cstdio>
#include<string>
#include<cstring>
#include<algorithm>
using namespace std;
int n,m,f[1005][1005],ans;
int main(){
    cin>>n>>m;
    for(int i = 1;i <= n;i++){
        for(int j = 1;j <= m;j++){
            scanf("%d",&f[i][j]);
        }
    }
    for(int i = 1;i <= n;i++){
        for(int j = m;j >= 1;j--){
            if(f[i][j]) f[i][j] = min(min(f[i-1][j],f[i-1][j+1]),f[i][j+1]) + 1;
            ans = max(ans,f[i][j]);
        }
    }
    cout<<ans;
    return 0;
}