I find the problem strikes a balance between tricky (needing specific knowledge of data structure and algorithm) and interesting (solvable with first-principle thinking). However, after understanding the tricky part, and working through the thinking, and implementing working code, I still could not really explain the intuition concisely. Hence this writing. Let’s hope that it helps you as much as it helped me. Problem Description You can find the problem description on Leetcode yourself.
