LeetCode题解(面试17.21)：直方图的水量(Python)

题目：​​原题链接​​（困难）

标签：栈、数组、双指针

解法一（双向遍历）：

class Solution:
    def trap(self, height: List[int]) -> int:
        size = len(height)

        # 正向遍历
        highest = 0
        left = [0] * size
        for i in range(size):
            highest = max(highest, height[i])
            left[i] = highest

        # 反向遍历
        highest = 0
        right = [0] * size
        for i in range(size - 1, -1, -1):
            highest = max(highest, height[i])
            right[i] = highest

        # 计算结果
        ans = 0
        for i in range(size):
            ans += min(left[i], right[i]) - height[i]
        return ans