luogu_1387 最大正方形

#include<bits/stdc++.h>

using namespace std;

int n,m,a[110][110],maxn;

int min(int a,int b,int c){return min(a,min(b,c));}

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++)if(a[i][j]){

a[i][j]=min(a[i-1][j],a[i][j-1],a[i-1][j-1])+1;

maxn=max(a[i][j],maxn);

}

printf("%d\n",maxn);

return 0;

}