Trapping Rain Water

1def trap(height: List[int]) -> int:
2    left, right = 0, len(height) - 1
3    left_max = right_max = 0
4    water = 0
5    
6    while left < right:
7        if height[left] < height[right]:
8            left_max = max(left_max, height[left])
9            water += left_max - height[left]
10            left += 1
11        else:
12            right_max = max(right_max, height[right])
13            water += right_max - height[right]
14            right -= 1
15    
16    return water