Blog
Deep-dives and written walkthroughs, pair them with the videos.
- Arrays & Hashing
Two Sum, From Brute Force to O(n)
The classic warm-up. Learn how a hash map turns an O(n²) scan into a single O(n) pass.
2026-06-20 - Arrays & Hashing
Contains Duplicate, Your First Hash Set
A one-liner that teaches the single most useful data structure for interviews: the hash set.
2026-06-18 - Stack
Valid Parentheses, The Stack's Greatest Hit
Matching brackets is the canonical stack problem. Learn the push/pop pattern you'll reuse everywhere.
2026-06-15