[leetcode-42] Trapping Rain Water

LeetCode-42

Trapping Rain Water : Trapping rain water. find volume

note : Tip: swap

Answer

        :::python

class Solution:
    def trap(self, height: List[int]) -> int:
    if not height:
        return 0
    volume = 0
    left, right = 0, len(height) - 1
    left_max, right_max = height[left], height[right]
    while left < right:
        left_max, right_max = max(height[left], left_max), max(height[right], right_max)
        if left_max <= right_max:
            volume += left_max - height[left]
            left += 1
        else:
            volume += right_max - height[right]
            right -= 1
    return volume

Result : 126ms Memory: 16mb