1582 articles
Design a URL shortener like TinyURL using base-62 encoding with an incrementing counter or random key generation. A classic system design coding problem asked at Amazon, Google, and Bitly to test encoding, collision handling, and hashmap design.
Design a parking system with big, medium, and small spaces. O(1) addCar checks slot availability and decrements the counter—a warm-up problem testing array indexing and capacity management in FAANG phone screens.
Complete recap of all 20 system design DSA problems: pattern classification, time complexities, key data structures, and the decision framework for choosing the right design approach in FAANG interviews.
The complete binary tree interview playbook for 2026 — 9 patterns, ready-to-paste DFS/BFS templates, and a curated index of 75 LeetCode tree problems asked at Google, Meta, Amazon, Apple, and Microsoft.
LeetCode 104 — Maximum Depth of Binary Tree, asked by Amazon, Google, Meta and Apple as a phone-screen warmup. Solve it in one line of recursive DFS or with iterative BFS level counting in O(n) time.