Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it is able to trap after raining.
height = elevation map array
total trapped water
Example 1:
Input:
height = [0,1,0,2,1,0,1,3,2,1,2,1]
Output:
6
Explanation:
Water is trapped between elevations as shown.
Example 2:
Input:
height = [4,2,0,3,2,5]
Output:
9
Explanation:
Trapped water amount is 9 units.