leetcode-221-最大正方形

题目描述：

 方法一：动态规划

class Solution:
    def maximalSquare(self, matrix: List[List[str]]) -> int:
        if not matrix:
            return 0
        row = len(matrix)
        col = len(matrix[0])
        dp = [[0 for _ in range(col+1)] for _ in range(row + 1)]
        res = 0
        for i in range(row):
            for j in range(col):
                if matrix[i][j]=='1':
                    dp[i+1][j+1] = min(dp[i+1][j],dp[i][j],dp[i][j+1])+1
                    res = max(res, dp[i+1][j+1] ** 2)
        return res

class Solution:
    def maximalSquare(self, matrix: List[List[str]]) -> int:
        res=0
        for i in range(len(matrix)):
            for j in range(len(matrix[0])): 
                matrix[i][j]=int(matrix[i][j])
                if i==0 or j==0:
                    res=max(res,matrix[i][j])
                    continue

                if matrix[i][j]==0:continue

                matrix[i][j]=min(matrix[i-1][j],matrix[i][j-1],matrix[i-1][j-1])+1               
                res=max(res,matrix[i][j])

        return res**2