221. Maximal Square

JIAKAOBO

LeetCode

感谢赞助!

• ㊗️
• 大家
• offer
• 多多！

Problem

Given a 2D binary matrix filled with 0’s and 1’s, find the largest square containing only 1’s and return its area.

Example:

Input:

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

Output: 4

Code

class Solution {
    public int maximalSquare(char[][] matrix) {
        if(matrix == null || matrix.length == 0) return 0;

        int m = matrix.length;
        int n = matrix[0].length;
        int res = 0;

        int[][] dp = new int[m + 1][n + 1];

        for(int i = 1; i <= m; i++){
            for(int j = 1; j <= n; j++){
                if(matrix[i - 1][j - 1] == '1'){
                    dp[i][j] = Math.min(Math.min(dp[i][j - 1], dp[i - 1][j - 1]), dp[i - 1][j]) + 1;
                    res = Math.max(res, dp[i][j]);
                }
            }
        }
        return res * res;
    }
}