LeetCode 84. 柱状图中最大的矩形
题目链接：84. 柱状图中最大的矩形 - 力扣（LeetCode）

和接雨水还挺像的。

代码：

#python
class Solution:
    def largestRectangleArea(self, heights: List[int]) -> int:
        heights.insert(0, 0)
        heights.append(0)
        stack = [0]
        result = 0
        for i in range(1, len(heights)):
            while stack and heights[i] < heights[stack[-1]]:
                mid_height = heights[stack[-1]]
                stack.pop()
                if stack:
                    # area = width * height
                    area = (i - stack[-1] - 1) * mid_height
                    result = max(area, result)
            stack.append(i)
        return result

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