leetcode 221. Maximal Square

Given a 2D binary matrix filled with 0's and 1's, find the largest square containing all 1's and return its area.
For example, given the following matrix:

1 0 1 0 0
1 0 1 1 1
1 1 1 1 1
1 0 0 1 0

Return 4.
、

class Solution {
	bool checkboader(vector<vector<char>>& matrix,int rightdownX,int rightdownY,int len)
	{
		for(int i=rightdownY-len;i<=rightdownY;i++)
			if(matrix[i][rightdownX]=='0')
				return false;
		for(int i=rightdownX-len;i<=rightdownX;i++)
			if(matrix[rightdownY][i]=='0')
				return false;
		return true;
	}
	void get_bigger(vector<vector<char>>& matrix,int leftupX,int leftupY,int&maxsquare)
	{
		int kk=1;
		while(leftupX+kk<matrix[0].size()&&leftupY+kk<matrix.size()&&
			checkboader(matrix,leftupX+kk,leftupY+kk,kk))
			kk++;
		//if(leftupX+kk>=matrix[0].size()||leftupY+kk>=matrix.size())

		if(kk>maxsquare)
			maxsquare=kk;
	}
public:
	int maximalSquare(vector<vector<char>>& matrix) {
		if(matrix.empty())
			return 0;
		if(matrix[0].empty())
			return 0;
		int maxsquare=0;
		for(int i=0;i<matrix.size()-maxsquare;i++)
			for(int j=0;j<matrix[0].size()-maxsquare;j++)
			{
				if(matrix[i][j]=='1')
				{
					get_bigger(matrix,j,i,maxsquare);
				}
				//cout<<i<<"  "<<j<<endl;
			}
			return maxsquare*maxsquare;
	}
};

accepted