cpp-flashcards/leetcode/AGENTS.md

AGENTS.md — leetcode/

What This Is

An idempotent extractor that pulls the NeetCode roadmap dependency graph and problem list from the live site (neetcode.io). Outputs structured JSON, Graphviz DOT, and Emacs org-mode files.

How It Works

NeetCode is an Angular SPA. The data we need is split across lazy-loaded JS chunks:

1. HTML (/roadmap) — contains the <script> tags pointing to the runtime and main bundle filenames (content-hashed).
2. Runtime JS — maps chunk IDs to content hashes: 7669:"fc6133d290d8d0ad".
3. Main bundle (main.*.js) — contains all ~965 problems with fields: problem, pattern, link, difficulty, code, flags (neetcode150, blind75, neetcode250, premium).
4. Chunk 7669 — contains the graph nodes (id, name, parentId[]) and course-to-topic mappings. The parentId array is the edge list — each entry points to a prerequisite topic.

The script (extract.mjs) resolves the hashed filenames at runtime, downloads the chunks, and regex-extracts the data structures.

Running

node extract.mjs                  # writes to ./out/ + org/study_deck_02/roadmap.org
node extract.mjs --stdout         # prints full JSON to stdout
node extract.mjs --cache /tmp/nc  # custom cache directory
node scaffold-notes.mjs           # create missing note files (skips existing)
node populate-notes.mjs           # fill notes with descriptions + code stubs
node populate-notes.mjs --force   # overwrite existing content
node populate-notes.mjs --dry-run # show what would change

Downloads are cached in .cache/ (gitignored). Re-runs are instant and produce byte-identical output.

Scripts

Script	Purpose
extract.mjs	Fetch NeetCode data, write JSON/DOT/org files
scaffold-notes.mjs	Create empty note files for each problem
populate-notes.mjs	Fetch problem descriptions + code stubs from LeetCode API

Output Files

File	Contents
out/roadmap.json	Full data: graph, all 965 problems, courses
out/roadmap-neetcode150.json	NeetCode 150 only (199 problems)
out/roadmap.dot	Graphviz DOT (render with dot -Tsvg)
out/roadmap.org	Org-mode with TODO checklists, Python/C++ links (moved to org/study_deck_02/roadmap.org)
neetcode-roadmap-graph.json	Standalone edge list (manual copy)
neetcode-roadmap.dot	Standalone DOT (manual copy)

The Dependency Graph

18 topics, 21 edges, topologically ordered:

Arrays & Hashing
├── Two Pointers
│   ├── Sliding Window
│   ├── Linked List → Trees
│   └── Binary Search → Trees
│       ├── Tries
│       ├── Heap / Priority Queue → Intervals, Greedy, Advanced Graphs
│       └── Backtracking
│           ├── Graphs → Advanced Graphs, 2-D DP, Math & Geometry
│           └── 1-D Dynamic Programming → 2-D DP, Bit Manipulation
└── Stack

Org-Mode Format

Each topic is a * TODO heading with a [/] cookie for progress. Problems are ** TODO sub-headings with difficulty tags (:easy:, :medium:, :hard:). Each problem has a properties drawer with links to LeetCode, GitHub solutions (Python/C++), and video. A Notes: line links to the personal notes file at org/study_deck_02/dsa/<topic>/<problem>.org.

Notes Files

org/study_deck_02/dsa/<topic>/<code>.org — one per NeetCode 150 problem (199 total). Scaffolded by scaffold-notes.mjs. Template:

* TODO 0217. Contains Duplicate :easy:
#+PROPERTY: STUDY_DECK_02
:PROPERTIES:
:NEETCODE: [[file:../../roadmap.org::*0217. Contains Duplicate][Roadmap]]
:END:

#+begin_src cpp

#+end_src

Run node scaffold-notes.mjs to create missing note files (skips existing).

Updating

Just re-run node extract.mjs. It fetches fresh data from the site (cached locally). If NeetCode changes their chunk structure, the regexes in extractGraphNodes() and extractProblems() will need updating.

Dependencies

None. Uses only Node.js built-ins (fs, path, url, fetch). Requires Node 18+ for native fetch.