區間最大子正方形問題。
預處理後二分答案驗證

AC Code：

#include<bits/stdc++.h>
#define maxn 1005
#define lim 10
using namespace std;

int n,m,dp[maxn][maxn],s[maxn][maxn],f[10][10][maxn][maxn],lg[1<<10];
inline int Query(int a,int b,int c,int d)
{
	if(a>c || b>d) return 0;
	int l1 = lg[c - a + 1]  ,l2=
 
lg[d - b + 1];
	return max(
		max(f[l1][l2][a][b],f[l1][l2][c-(1<<l1)+1][b]),
		max(f[l1][l2][a][d-(1<<l2)+1],f[l1][l2][c-(1<<l1)+1][d-(1<<l2)+1])
	);
}

int main()
{
	scanf("%d%d",&n,&m);
	for(int i=1;i<=n;i++)
		for(int j=1;j<=m;j++)
			scanf("%d",&s[i][j]
 
);
	for(int i=1;i<=n;i++)
		for(int j=1;j<=m;j++)
			if(s[i][j])
				if(i==1 || j==1) dp[i][j] = 1;
				else dp[i][j] = min(dp[i-1][j],min(dp[i][j-1],dp[i-1][j-1]))+1;
	for(int a=0;a<lim;a++)
		for(int b=0;b<lim;b++)
			for(int i=1;i<=n;i++)
				for(int j=1;j<=m;j++)
				{
					if(a==
 
0 && b==0) f[a][b][i][j] = dp[i][j];
					else if(a==0)
					{
						int v = j + (1<<b-1);
						f[a][b][i][j] = max(f[a][b-1][i][j],f[a][b-1][i][v]);
					}
					else if(b==0)
					{
						int u = i + (1<<a-1);
						f[a][b][i][j] = max(f[a-1][b][i][j],f[a-1][b][u][j]);
					}
					else 
					{
						int u = i + (1<<a-1) , v = j + (1<<b-1);
						f[a][b][i][j] = max(
							max(f[a-1][b-1][i][j],f[a-1][b-1][u][j]) , 
							max(f[a-1][b-1][i][v],f[a-1][b-1][u][v])
						);
					}
				}
	for(int i=2;i<maxn;i++) lg[i] = lg[i>>1] + 1;
		
	int q,a,b,c,d;
	for(scanf("%d",&q);q--;)
	{
		scanf("%d%d%d%d",&a,&b,&c,&d);
		int L = 0 , R = min(c-a+1,d-b+1) , mid;
		for(;L<R;)
		{	mid = (L+R+1) >> 1;
			if(Query(a+mid-1,b+mid-1,c,d) >= mid) L = mid;
			else R = mid - 1;
		}
		printf("%d\n",L);
	}
}