https://leetcode.com/discuss/interview-question/891868/Phone-Interview-Coinbase https://leetcode.com/problems/design-in-memory-file-system/ https://codereview.stackexchange.com/questions/240622/file-system-oop https://www.youtube.com/watch?v=SJmYTJEVa_U&t=1278s&ab_channel=WorkWithGoogler