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



class Solution {
public:
//dp[i][j] = min(dp[i][j-1], dp[i-1][j], dp[i-1][j-1]) + 1
    int maximalSquare(vector<vector<char>>& matrix) {
        
        int m=matrix.size();
        if(m<1)
            return 0;
        int n=matrix[0].size();
        if(n<1)
            return 0;
            
        int max=0;
        vector< vector<int> > dp(m,vector<int>(n,0));
        
        for(int i=0;i<m;i++)
        {
            dp[i][0]=matrix[i][0]=='0'?0:1;
            if(matrix[i][0]=='1')
                max=1;
        }
            
        for(int i=0;i<n;i++)
        {
            dp[0][i]=matrix[0][i]=='0'?0:1;
            if(matrix[0][i]=='1')
                max=1;
        }
        for(int i=1;i<m;i++)
            for(int j=1;j<n;j++)
            {
                if(matrix[i][j]=='1')
                {
                    dp[i][j]=Min(dp[i][j-1],dp[i-1][j],dp[i-1][j-1])+1;
                    if(dp[i][j]>max)
                        max=dp[i][j];
                }
            }
        return max*max;
    }
    
    int Min(int x,int y,int z)
    {
        if(x>y)
            x=y;
        if(x>z)
            return z;
        else
            return x;
    }
};