leetcode 85. Maximal Rectangle

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

For example, given the following matrix:

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

Return 6.

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class Solution(object):
    def maximalRectangle(self, matrix):
        """
        :type matrix: List[List[str]]
        :rtype: int
        """
        if len(matrix) == 0 or len(matrix[0]) == 0:
            return 0
        n = len(matrix[0])#列
        height = [0]*(n+1)
        ans = 0
        for row in matrix:
            for i in range(n):
                if row[i] == '0':
                    height[i] = 0
                else:
                    height[i] += 1
            stack = [-1]
            for i in range(n+1):
                while height[i] < height[stack[-1]]:
                    h = height[stack.pop()]
                    w = i - stack[-1] - 1
                    ans = max(ans,w*h)
                stack.append(i)
        return ans