85. Maximal Rectangle

85. Maximal Rectangle

class Solution:
    def maximalRectangle(self, matrix: List[List[str]]) -> int:
        def hist(heights):
            stack,ans=[],0
            for i,h in enumerate(heights+[0]):
                while stack and heights[stack[-1]]>=h:
                    H=heights[stack.pop()]
                    W=i if not stack else i-stack[-1]-1
                    ans=max(ans,H*W)
                stack.append(i)
            return ans

        if not matrix or not matrix[0]: return 0

        m,n,ans=len(matrix[0]),len(matrix),0
        row=[0]*m
        for i in range(n):
            for j in range(m):
                row[j]=0 if matrix[i][j]=='0' else row[j]+1
            ans=max(ans,hist(row))
        return ans

二维单调栈

递增栈