| name | add-solution |
| description | Add a LeetCode solution write-up to this repo following its conventions. Use when the user wants to add/create a solution for a LeetCode problem (given a URL, problem id/title, and/or code in one or more languages). Creates the difficulty/<id>.<Title> folder, writes solution.md (+ optional description.md), and updates the README index. |
Add LeetCode Solution
Automates adding a new solution to this repository. Follow these steps in order.
1. Resolve the problem metadata
You need: problem id, exact title, difficulty (Easy/Medium/Hard), and the
statement/examples/constraints.
-
If given a LeetCode URL, extract the titleSlug (the path segment after
/problems/).
-
WebFetch on leetcode.com usually returns 403 — do not rely on it. Instead
query the GraphQL API for everything in one call:
curl -s 'https://leetcode.com/graphql' \
-H 'Content-Type: application/json' -H 'User-Agent: Mozilla/5.0' \
--data '{"query":"query q($titleSlug:String!){question(titleSlug:$titleSlug){questionFrontendId title difficulty content}}","variables":{"titleSlug":"<TITLE-SLUG>"}}'
questionFrontendId is the problem id, difficulty maps to the folder, and
content is the HTML statement (convert to clean markdown for description.md).
-
If the user already supplied id/title/difficulty, trust those; only fetch what's
missing.
2. Create the folder
<Difficulty>/<id>.<Problem-Title-With-Hyphens>/
- Difficulty is
Easy, Medium, or Hard (matches LeetCode).
- Title: replace spaces with hyphens, keep the original casing and roman numerals
(e.g.
3739.Count-Subarrays-With-Majority-Element-II).
- Use
mkdir -p.
3. Write solution.md
Use the repo template exactly:
# Intuition
Brief explanation of the key insight.
# Approach: <Technique Name>
Step-by-step algorithm description.
# Complexity
- Time complexity: $$O(...)$$
- Space complexity: $$O(...)$$
# Code
## Go
```go
...
Rust
...
Rules:
- One `solution.md` with `## Go`, `## Rust`, `## C++` sub-sections under `# Code`
when documenting multiple languages. Use a single language-specific file
(`solution-go.md`, `solution-rust.md`, `solution-cpp.md`) only when the user
asks for that layout or just one language with extra context.
- Use `$$...$$` (KaTeX) for **all** math, including big-O. GitBook's Git sync only
renders double-dollar math; single `$...$` shows up as literal text there.
GitHub renders `$$...$$` too, so it works on both. Do **not** use single `$...$`
or plain text for formulas.
- Write complexity on one line, e.g. `- Time complexity: $$O(n \log n)$$, where `n`
is the array length.` (prose variables can stay in backticks; formulas go in `$$`).
- Use LaTeX inside the math: `\log`, `\frac{a}{b}`, `\lceil x \rceil`, `\cdot`,
`\times`, `\le`, `\alpha(n)`, exponents `x^2` / `10^5`, subscripts `a_i`.
- After writing, run `./tools/mathfix.py <file>` to convert any stray `$...$` to
`$$...$$` (it skips code blocks, inline code, and currency, and is idempotent).
- Keep explanations concise and focused on **why** the approach works.
- Paste the user's code verbatim (only fix obvious formatting); do not invent a
different algorithm than what they provided.
- No empty placeholder sections.
## 4. Write `description.md` (optional but preferred)
Convert the GraphQL `content` HTML into markdown: a title heading, the statement,
`## Example N` blocks (in fenced ```text), and a `## Constraints` list. Use `^` for
exponents (e.g. `10^5`).
## 5. Update `README.md`
`README.md` has per-difficulty tables and counts.
1. Add a row to the matching difficulty table, kept in ascending id order:
```md
| <id>. <Title> | [Link](https://leetcode.com/problems/<slug>/) | [main](<Difficulty>/<folder>/solution.md) |
- The solution column links each variant:
main for solution.md, or the
suffix label for solution-<variant>.md, joined with ·
(e.g. [go](...) · [rust](...) · [main](...)).
- Increment the difficulty header count, e.g.
### Hard (27) → ### Hard (28).
- Increment the total near the top:
Total: **N** problems with at least one solution file.
Also update the count in CLAUDE.md ("The index currently lists N problems.")
if you bump the README total.
6. Normalize math in markdown
Convert any single-dollar $...$ to GitBook-compatible $$...$$ (KaTeX) so the
math renders on both GitBook and GitHub:
./tools/mathfix.py <new-solution-file>
Pass a specific file path to limit the scope. Use --check to preview changes.
The script skips code blocks, inline code, and currency, and is idempotent.
7. Regenerate the GitBook table of contents
The repo is published as a GitBook space synced from main (.gitbook.yaml →
SUMMARY.md). After creating the folder and solution file(s), regenerate the
table of contents so the new problem appears in the nav:
./tools/gen-summary.sh
This rewrites SUMMARY.md from the current folder layout (grouped by difficulty,
sorted by id, variant files nested). Commit the updated SUMMARY.md alongside the
solution so GitBook picks it up on the next push. (If the Docsify sidebar is also
in use, run ./tools/gen-sidebar.sh to refresh _sidebar.md as well.)
8. Git (only if the user asks)
Do not commit or open a PR unless asked. When asked:
- Create a feature branch (e.g.
add-<id>-<short-slug>).
- Commit message:
Add solution for <id>. <Problem Title>
- Open a PR against
main; do not push unless asked.
Verification checklist
