maxSizeSquare.cpp

#include<iostream>
using namespace std;

const int Nmax = 1001;

bool a[Nmax][Nmax];
int n,m, maxLen[Nmax][Nmax]; //maxLen[i][j] = max. x such as (i -x +1, j-x+1) -> (i,j) full of 1's
							 //maxLen[i][j] = min(maxLen[i-1][j], maxLen[i][j-1], maxLen[i-1][j-1]) +1 , if a[i][j]=1
							 //				= 0, otherwise

int maxSizeSquare(bool a[][Nmax], int n, int m){ //passing matrices as arguments the size of the first argument is not
												 // that mandatory, but the second one is mandatory
	int ans = 0;
	for(int i=1;i<=n;i++)
		for(int j=1;j<=m;j++){
			if(a[i][j] == false)
				maxLen[i][j] = 0;
			else
				maxLen[i][j] = min(maxLen[i][j-1] , min(maxLen[i-1][j], maxLen[i-1][j-1])) + 1;
			ans = max(ans, maxLen[i][j]);
		}
		return ans;
}	

int main(){
	cin>>n>>m;
	for(int i=1;i<=n;i++)
		for(int j=1;j<m;j++)
			cin>>a[i][j];
	cout<<maxSizeSquare(a,n,m);
	return 0;
}