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.

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