Leetcode 221. Maximal Square

Seawolf

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 Solution:
    def maximalSquare(self, matrix: List[List[str]]) -> int:
        if matrix == None or len(matrix) == 0 or len(matrix[0]) == 0:
            return 0
        size = [[0 for _ in range(len(matrix[0]) + 1)] for _ in range(len(matrix) + 1)]
        result = 0
        for i in range(1, len(matrix) + 1):
            for j in range(1, len(matrix[0]) + 1):
                if matrix[i - 1][j - 1] == '1':
                    size[i][j] = min(size[i - 1][j], size[i][j - 1], size[i - 1][j - 1]) + 1
                    result = max(result, size[i][j])
        return result * result