Volume 1: Field notebook1/1
  1. 01Entries 1-5

Chapter 01 of 01

Entries 1-5

5 lessons16 min reading
  1. 01LeetCode Easy Notebook - the planHow I am going to turn Easy problems into a real notebook: pattern first, brute force second, optimized solution third, and complexity last.3 min read
  2. 02LeetCode #20 - Valid Parentheses, and the stack instinctA small string problem that teaches the core stack pattern: the most recent opener must be the first one closed.4 min read
  3. 03LeetCode #70 — Climbing Stairs: Fibonacci in disguiseWhy 'how many ways' problems are recurrences in disguise — from exponential recursion to my memoized 0ms solution, plus the O(1) two-variable finish.4 min read
  4. 04My remix: Two Sum, but it's 100M numbers and you get 512 MBI made up my own follow-up: what happens to the hash-map solution when the array doesn't fit in memory? Duplicates, negatives, and external partitioning.3 min read
  5. 05LeetCode #1 — Two Sum, and the hash map reflexThe classic warm-up: from O(n²) brute force to a one-pass hash map, and the pattern it teaches you to spot everywhere.1 min read