【leetcode每日刷題】221. Maximal Square

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

 

class num221 {
    public int maximalSquare(char[][] matrix) {
        int m = matrix.length;
        if(m == 0) return 0;
        int n = matrix[0].length;
        int[][] dp = new int[m+1][n+1];
        int max = 0;
        for(int i=1; i<=m; i++){
            for(int j=1; j<=n; j++){
                if(matrix[i-1][j-1] == '0'){
                    dp[i][j] = 0;
                }else{
                    dp[i][j] = Math.min(dp[i-1][j], Math.min(dp[i][j-1], dp[i-1][j-1])) + 1;
                }
                max = max < dp[i][j] ? dp[i][j] : max;
            }
        }
        return max*max;
    }
}