[LeetCode] Maximal Square

Problem:

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.

Solution:

Dynamic Programming, explanation: 
http://bookshadow.com/weblog/2015/06/03/leetcode-maximal-square/

Java Code:

public class Solution {
    public int maximalSquare(char[][] matrix) {
        if (matrix == null || matrix.length == 0) {
            return 0;
        }
        
        int[][] dp = new int[matrix.length][matrix[0].length];
        int max = 0;
        
        for (int i = 0; i < matrix.length; i++) {
            dp[i][0] = matrix[i][0] == '1' ? 1 : 0;
            max = Math.max(max, dp[i][0]);
        }
        
        for (int j = 0; j < matrix[0].length; j++) {
            dp[0][j] = matrix[0][j] == '1' ? 1 : 0;
            max = Math.max(max, dp[0][j]);
        }
        
        
        for (int i = 1; i < matrix.length; i++) {
            for (int j = 1; j < matrix[0].length; j++) {
                dp[i][j] = matrix[i][j] == '1' ? 
                Math.min(Math.min(dp[i - 1][j], dp[i][j - 1]), dp[i - 1][j - 1]) + 1 : 0;
                max = Math.max(max, dp[i][j]);
            }
        }
        
        return (int)Math.pow(max, 2);
    }
}