LeetCodeAnimation

LeetCode solutions explained with animations: how pointers move, how states change, how recursion unfolds, and why boundary cases hold. This GitHub copy is the public index and historical assets; full step-through, replay, speed control, and voice walkthroughs live in the website version.

If this project helps you, a Star keeps it visible and supports continued updates.

🚧 2026 Major Version In Progress

This repo is not a one-off archive. A major 2026 upgrade is underway — only shipped / in-progress facts are listed:

• ✅ Three-language reference code: every solution ships Python / C++ / Java implementations, Python by default.
• ✅ AI tutor "Xiao Ou": an AI algorithm tutor that answers follow-up questions on ideas and edge cases while you solve.
• ✅ Voice walkthroughs in Wu Shixiong's voice: the animation narrates as it plays; the voice is AI-synthesized (Wu Shixiong's voice, authorized). Hit 🔊 in the player.
• 🚧 Full quality pass over 299 problems: a problem-by-problem quality review and remake, shipping in batches and synced back into this repo's index.

Progress flows into the "Current Index" below and sync-log.md via the sync scripts.

Website-Style Animation Previews

These GIFs are captured from the website player. Click any image to jump straight to its problem page (full step playback, three-language code, and voice walkthrough are all in the website version).

Two Sum Scan the array while the hash table grows, then see exactly where the complement is found.	Trapping Rain Water Bar heights, boundaries, and trapped water are shown as separate moving states.
Number of Islands The DFS coloring process unfolds cell by cell, making connected components easier to inspect.	Linked List Cycle Slow and fast pointers move on the same list, so the meeting point becomes visible.

↑ The website version also lets you step, replay, change speed, and listen — open the interactive version →

Highlights

• Animation-first: understand the process first, then return to the code. Many problems keep GIFs or step-by-step animation assets.
• Three-language code: each solution ships Python / C++ / Java reference implementations.
• Structured data: data/manifest.json can be consumed by scripts for indexing, link checks, or downstream tooling.
• Continuous sync: when the website adds or adjusts animations, scripts sync them back to GitHub — the repo is not a static archive.

Current Index

The numbers below are injected by tools/scripts/build-readme.js from docs/data/manifest.json. Do not edit by hand.

What the numbers mean: 256 is the number of LeetCode animations already synced into this repo (computed by scripts from the website-side study_index.js → manifest.json). The 299 mentioned above is algomooc.com's full animation catalog (including advanced problems and topic sets, from the site's content-stats single source) — a larger set than this repo's synced LeetCode subset. Both numbers are script-managed and never hand-typed: 256 comes from this repo's manifest; 299 is backfilled from the site's content-stats (see the siteTotal field in data/stats.json).

Content Map

npm run review:site

npm run sync        # update manifest / number index / topic index / sync log
npm run validate    # validate the manifest
node tools/scripts/build-readme.js --write   # re-inject README number blocks + stats.json

⭐ Star it to follow the updates

This project grew from hand-drawn animations to where it is today on the encouragement of every Star. If it helped you truly understand a problem, a Star is the most concrete support for continued updates.

📌 Content is continuously synced from algomooc.com — when the website updates, the repo index follows via scripts.

中文

See ../README.md.