In this post we will solve the LeetCode 42. Trapping Rain Water problem using the Java programming language and the VSCode IDE on a Windows computer. The simplest approach is to develop the code on the online IDE provided by LeetCode.

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. Constraints: o n == height.length o 1 <= n <= 2 * 10^4 o 0 <= height[i] <= 10^5 Related Topics: * Array * Two Pointers o Dynamic Programming o Stack o Monotonic Stack

The diagram on the LeetCode page is very useful to get the general idea of what the problem is. It also helps to draw the diagram on a piece of paper and figure out an approach. We need to calculate the amount of water on each cell and add them together to get our result. The trick is in how we implement the task. Continue reading “LeetCode 42. Trapping Rain Water in Java”