CLAUDE.md

CLAUDE.md

Guidance for AI assistants working in this repository.

Project overview

This repo stores LeetCode algorithm solutions as markdown write-ups. Solutions are grouped by difficulty and problem id:

Easy/
Medium/
Hard/
  └── <problem_id>.<Problem-Title-With-Hyphens>/
        ├── solution.md          # primary write-up (required)
        ├── description.md       # optional problem statement
        ├── solution-go.md       # optional language-specific file
        ├── solution-rust.md
        └── solution-cpp.md

Telegram group: https://t.me/+ST0unit9nTRkYjhl

Conventions

Directory naming

• Format: <problem_id>.<Problem-Title-With-Hyphens>
• Examples:
  • Medium/1833.Maximum-Ice-Cream-Bars/
  • Easy/1636.Sort-Array-By-Increasing-Frequency/
• Place the folder under the correct difficulty directory (Easy, Medium, or Hard).

Solution files

• Default file name: solution.md
• Use language-specific files when only one language is documented or when a language needs extra context:
  • solution-go.md
  • solution-rust.md
  • solution-cpp.md
• When documenting multiple languages for the same problem, prefer one solution.md with ## Go, ## Rust, etc. under # Code.

Solution markdown template

Follow the structure used across the repo:

# 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

...

Notes:

- Use `$$...$$` (KaTeX) for all complexity/math expressions, e.g.
  `$$O(n \log n)$$`. GitBook's Git sync only renders double-dollar math; single
  `$...$` shows up as literal text there. GitHub renders `$$...$$` too, so this
  works on both. Plain text loses real typesetting (`\frac`, `\lceil`, ...).
- Run `./tools/mathfix.py` on new solution files to convert any `$...$` to
  `$$...$$` (it skips code blocks, inline code, and currency).
- Keep explanations concise and focused on why the approach works.
- Match the documentation style of nearby problems in the same folder/difficulty.
- Optional `description.md` can contain the LeetCode problem statement, examples, and constraints.

### Markdown style

Follow: <https://github.com/DavidAnson/markdownlint/blob/v0.35.0/doc/Rules.md>

### Git workflow

- Create a feature branch for new solutions.
- Commit message style: `Add solution for <id>. <Problem Title>`
- Open a PR against `main`; do not push unless asked.

## README maintenance

`README.md` contains a full solutions index grouped by difficulty (`Easy`, `Medium`, `Hard`). When adding a new problem:

1. Create the problem folder and solution file(s) under the correct difficulty directory.
2. Add a row to the matching difficulty table in `README.md` with:
   - Problem id and title
   - LeetCode link
   - Link(s) to each `solution*.md` variant (`main` for `solution.md`, or the suffix for `solution-<variant>.md`)

The index currently lists **189** problems. Regenerate the tables from the repo if many entries change at once.

## Common patterns in this repo

- **Hash map / frequency counting** — e.g. 219, 1636, 1833
- **Stack** — e.g. 155, 921
- **Union-Find** — e.g. 1579
- **Binary search** — e.g. 875, 1760
- **DFS / BFS** — e.g. 1905, 1110
- **Trie** — e.g. 208
- **Segment tree** — e.g. 307

## What not to do

- Do not post full LeetCode test harness code unless the repo already uses that style for the problem.
- Do not create commits or PRs unless the user asks.
- Do not add unrelated refactors when adding a single solution.
- Do not create empty placeholder sections; prefer concise, complete write-ups.