算法D60 | 单调栈3 | 84.柱状图中最大的矩形

有了之前单调栈的铺垫，这道题目就不难了。 

代码随想录

今天是训练营最后一天，恭喜坚持两个月的录友们，接下来可以写一篇自己 代码随想录一刷的总结。好好回顾一下，这两个月自己的博客内容，以及自己的收获。 

Python:

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

C++:

class Solution {
public:
    int largestRectangleArea(vector<int>& heights) {
        heights.insert(heights.begin(), 0);
        heights.push_back(0);
        stack<int> stk;
        stk.push(0);
        int result = 0;
        for (int i = 1; i < heights.size(); i++) {
            while (heights[i] < heights[stk.top()]) {
                int h = heights[stk.top()];
                stk.pop();
                int w = i - stk.top() - 1;
                result = max(result, w*h);
            }
            stk.push(i);
        }
        return result;
    }
};