cs.thefarshad.com

An interactive computer science reference: short lessons paired with visualizers, plus practice problems you can run in the browser. Live at cs.thefarshad.com.

Everything runs client-side — no account or backend required. Themes and fonts are switchable, and lesson/problem progress is saved locally in the browser.

Tracks

• Mathematics — algebra & functions, trigonometry, exponents & logarithms, logic & sets
• Data Structures — linked lists, stacks & queues, hash tables, binary search trees / AVL, heaps
• Algorithms — sorting, binary search, pathfinding, recursion, dynamic programming, graph traversal
• C++ — getting started, the STL
• CS Systems — Big-O & complexity, operating systems, networking, database internals
• System Design — scaling, data at scale, consensus, a URL-shortener case study
• SQL — querying, joins (with an in-browser SQLite playground)
• Git — the commit graph, merging & rebasing (interactive DAG)
• Bash — the shell & filesystem, pipes & filters (sandboxed terminal)
• Machine Learning — gradient descent, supervised learning
• RL & Math — reinforcement learning, Markov chains, optimization
• Robotics — kinematics, PID control, path planning, perception & SLAM
• Quantum Computing — qubits & superposition, quantum gates

Most lessons embed a step-through visualizer (sorting, trees, pathfinding, gradient descent, a gridworld RL agent, a single-qubit simulator, and more).

Practice problems

Practice problems with an in-browser judge. Python runs via Pyodide and JavaScript runs natively, both client-side. Each problem ships reference solutions in Python, JavaScript, C++, Java, and pseudocode.

How it works

• Astro with React islands and Tailwind CSS v4
• Static build deployed to GitHub Pages
• In-browser execution: Pyodide (Python), native JavaScript, and sql.js (SQLite)

Project structure

apps/web/
  src/
    content/lessons/   MDX lessons, one folder per track
    components/viz/     interactive visualizers
    components/...      UI, problem runner, code tabs
    pages/              routes (/learn/..., /problems/...)
    lib/                tracks, problems, code runners, icons
  scripts/verify.ts     automated correctness checks for the algorithm logic
.github/workflows/      build + deploy to GitHub Pages

Develop

cd apps/web
npm install
npm run dev      # local dev server
npm run build    # static build to dist/
npx tsx scripts/verify.ts   # run the algorithm correctness checks

Roadmap

A backend (accounts and cross-device progress sync, plus a compiled-language judge for C++/Java via Judge0) is planned; the site works fully without it.

License

GPL-3.0 — see LICENSE.