ROADMAP.md

Core 120 Roadmap

The goal is to grow deliberately from the original 98 questions to a balanced set of 120 high-value interview problems. New entries should add a missing pattern or strengthen a thin topic rather than duplicate an existing exercise.

Current progress: 120 / 120 problems (complete, plus 1 bonus problem)

Additional Basics

• Find Divisors of a Number

Batch 1 — Hashing, Sliding Window, and Trie

• Valid Sudoku
• Longest Repeating Character Replacement
• Permutation in String
• Design Add and Search Words Data Structure
• Word Search II

Batch 2 — Window, Stack, and Queue

• Fruit Into Baskets
• Subarray Product Less Than K
• Daily Temperatures
• Evaluate Reverse Polish Notation
• Implement Queue Using Stacks

Batch 3 — Linked Lists and Trees

• Reorder List
• Copy List with Random Pointer
• LRU Cache
• Validate Binary Search Tree
• Kth Smallest Element in a BST
• Binary Tree Right Side View
• Construct Binary Tree from Traversals

Batch 4 — Search, DP, and Graphs

• Search a 2D Matrix
• Koko Eating Bananas
• Word Break
• Pacific Atlantic Water Flow
• Minimum Spanning Tree

Definition of done

Every new problem must include:

• A source link, approach explanation, and time/space complexity.
• Type-annotated, Python 3.9-compatible code.
• Edge-case assertions or unit tests.
• A matching website catalog entry and updated documentation count.
• A passing python -m unittest discover -s tests -v run.