Rain Water Trapped

1 <= |A| <= 100000

First and only argument is the vector A

Return one integer, the answer to the question

Input 1:
A = [0, 1, 0, 2]

Input 2:
A = [1, 2]

Output 1:
1

Output 2:
0

Explanation 1:
1 unit is trapped on top of the 3rd element.

Explanation 2:
No water is trapped.

public class Solution {
    public int trap(final int[] height) {
        if (height == null || height.length == 0) return 0;
 
        int left = 0, right = height.length - 1;
        int leftMax = 0, rightMax = 0;
        int trappedWater = 0;
 
        while (left < right) {
            if (height[left] < height[right]) {
                if (height[left] >= leftMax) {
                    leftMax = height[left];
                } else {
                    trappedWater += leftMax - height[left];
                }
                left++;
            } else {
                if (height[right] >= rightMax) {
                    rightMax = height[right];
                } else {
                    trappedWater += rightMax - height[right];
                }
                right--;
            }
        }
        return trappedWater;
    }
}

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

var trap = function(height) {
    if (height === null || height.length === 0) return 0;
 
    let left = 0,
        right = height.length - 1;
    let leftMax = 0,
        rightMax = 0;
    let trappedWater = 0;
 
    while (left < right) {
        if (height[left] < height[right]) {
            if (height[left] >= leftMax) {
                leftMax = height[left];
            } else {
                trappedWater += leftMax - height[left];
            }
            left++;
        } else {
            if (height[right] >= rightMax) {
                rightMax = height[right];
            } else {
                trappedWater += rightMax - height[right];
            }
            right--;
        }
    }
    return trappedWater;
};