Playground

Singleton, Factory, Builder, Adapter, Decorator, Strategy, Observer, Command, State, and more. Code in JS, Python, C#, Java.

MVC, MVVM, Clean Architecture, Hexagonal, Microservices, Event-Driven, Monolith. Pros, cons, folder structures.

SOLID (all 5), OOP pillars (all 4), DRY, KISS, YAGNI, Separation of Concerns, Composition over Inheritance. Bad vs good code.

AI → ML → Deep Learning → LLMs → RAG → Embeddings → Agents → MCP → A2A → ACP. The full stack explained simply.

Foundations to working code: Top K, Two Sum, Bracket Matcher, Caesar Cipher, Binary Search, Group Anagrams. 8 categories, 4-7 languages, with hints.

The hard stuff: LRU Cache, Word Ladder, Median Stream, Topological Sort, Coin Change, Edit Distance, Number of Islands, Validate BST. Hard, DP, Trees & Graphs — each with a "why optimal" deep-dive.

Classic challenges by topic: Strings, Math, Arrays, Search, DP, Trees, Graphs, Backtracking. Bite-sized practice, solutions in 4 languages.

Curated docs and references — Electron, MapLibre, MAVLink, MCP, A2A, FastAPI, .NET, React, Docker, and more. Organized by project.