Here is the interview question prompt, presented for reference.

Suppose you are given an elevation map composed of bars of different heights. You can assume that each bar has the same width. Can you figure out how much rain it will collect?

There can be different ways of representing an elevation map. We'll consider the simplest method of using a one dimensional array of non-negative numbers to represent the height at different places. The goal is to find out how much rain can be trapped when given an elevation map. The figure below shows various elevation maps and the units of rain water they can catch.

- Length of the array <=
`100000`

- Values in the array
`a[]`

>=`0`

- The final answer would fit in the Integer range(<
`2^32`

) - Ideal solution would run in
`O(n)`

time complexity and`O(1)`

space complexity

You can see the full challenge with visuals at this link.

**Challenges**
• Asked about 3 years ago by Jake from AlgoDaily

This is the main discussion thread generated for Trapping Rain Water.

There are no test cases and the environment does not support python

Thanks for the heads up and sorry for the miss! Added to the queue for the team to address, will update when resolved.

Thank you

Updated and resolved :-)