Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it can trap after raining.
This is a classic interview problem that tests your ability to optimize from O(n^2) to O(n) using two pointers or dynamic programming.
Examples
Example 1:
Input:height = [0,1,0,2,1,0,1,3,2,1,2,1]
Output:6
Explanation:In this case, 6 units of rain water are being trapped between the bars.