matrix1 = [["1","0","1","0","0"],["1","0","1","1","1"],["1","1","1","1","1"],["1","0","1","1","1"]]
 
class Solution:
    def maximalSquare(self, matrix):
        if not matrix or not matrix[0]:
            return 0
        m, n = len(matrix), len(matrix[0])
        dp = [[0] * n for _ in range(m)]
        ans = 0
        for i in range(m):
            for j in range(n):
                dp[i][j] = int(matrix[i][j])
                if i and j and dp[i][j]:
                    dp[i][j] = min(dp[i - 1][j], dp[i][j - 1], dp[i - 1][j - 1]) + 1
                ans = max(ans, dp[i][j])
        return ans * ans
s = Solution()
s.maximalSquare(matrix1)