LeetCode Daily Challenge Blog

Automated blog that fetches and posts LeetCode Daily Challenge problems every day at 00:00 UTC (midnight UTC).

Features

• Automated Daily Posts: GitHub Actions fetches the daily LeetCode problem and creates a new blog post automatically
• AI-Generated Solutions: Solutions in 19 programming languages with Pure CSS tabs
• Gemini-only AI: Gemini 3 Pro with Flash fallback on 429s
• Manual Regeneration: Update existing posts with new AI solutions via workflow or command line
• Jekyll-powered: Clean, fast static site hosted on GitHub Pages
• Modern UI: Beautiful, responsive design with dark mode support and code copy buttons
• Navigation: Archive, difficulty, and topic-based browsing
• Smart Caching: Efficient date-to-problem mapping for fast regeneration

Quick Start

1. Enable GitHub Pages

1. Go to repository Settings → Pages
2. Source: Deploy from a branch
3. Branch: Select master and /root folder
4. Save

2. Enable GitHub Actions Permissions

1. Go to repository Settings → Actions → General
2. Workflow permissions: Select "Read and write permissions"
3. Save

3. Configure AI Provider (Optional but Recommended)

To enable AI-generated solutions, add your API key:

Gemini (Only Provider)

Provider	Model	Secret Name	Get API Key
Gemini ✨	gemini-3-flash-preview	GEMINI_API_KEY	Get Key

Setup Instructions

1. Add API Key to GitHub Secrets

   • Go to repository Settings → Secrets and variables → Actions
   • Click "New repository secret"
   • Add GEMINI_API_KEY

2. Model Behavior

   • gemini-3-flash-preview

Notes:

• Only API keys go in Secrets (sensitive data)
• Without an API key, posts will only have problem descriptions without solutions

4. Test the Workflow

You can manually trigger the workflow to test:

1. Go to Actions tab
2. Select "LeetCode Daily Challenge" workflow
3. Click "Run workflow"
4. Choose AI model (default: Gemini)

Project Structure

scavienger.github.io/
├── _config.yml              # Jekyll configuration
├── Gemfile                  # Ruby dependencies
├── index.md                 # Home page
├── _layouts/
│   ├── home.html           # Homepage layout
│   └── post.html           # Post layout with TOC
├── _posts/                 # Auto-generated blog posts (nested by date)
│   └── _daily/             # Daily challenges
│       └── YYYY/MM/DD/     # Year/Month/Day folders
│           ├── slug.md     # Post file
│           └── *.txt       # Code snippets for each language
├── .github/
│   └── workflows/
│       ├── leetcode-daily.yml         # Daily automation workflow
│       ├── regenerate-solution.yml    # Manual regeneration workflow
│       └── generate-post-by-date.yml  # Generate by specific date
├── scripts/
│   ├── requirements.txt     # Python dependencies
│   ├── generate_posts.py    # Unified generator (fetch + solve + post)
│   ├── solve_with_ai.py     # AI solution generator
│   └── generate_post.py     # Jekyll post generator
├── data/                    # Cache files
│   └── daily_challenges.json   # Cached daily challenge mappings
└── assets/
    └── js/
        ├── dark-mode.js     # Dark mode toggle
        ├── code-tabs.js     # Code tab interactions
        └── code-copy.js     # Code copy functionality

How It Works

Daily Automation

1. Scheduled Trigger: GitHub Actions runs daily at 00:00 UTC (midnight UTC)
2. Fetch Challenges: Queries LeetCode GraphQL API for daily challenges
3. Cache Mapping: Stores date-to-problem mappings in data/daily_challenges.json
4. Fetch Problem Details: Gets problem content, examples, hints, and code templates
5. Save Snippets: Stores code templates for all 19 languages
6. AI Solutions: Generates solutions in 19 languages with approach and complexity analysis
7. Generate Post: Creates markdown file with Gemini solution and code tabs
8. Auto Deploy: GitHub Pages automatically builds and deploys the updated site

Manual Regeneration

Via GitHub Actions UI:

1. Go to Actions → Regenerate AI Solution for Post
2. Click Run workflow
3. Enter the post date (YYYY-MM-DD format, e.g., 2025-11-23)
4. Click Run workflow

Via Command Line:

# Set up environment
export GEMINI_API_KEY="your-key-here"

# Regenerate (Gemini only)
python scripts/generate_posts.py 2025-11-23

This is useful for:

• Regenerating solutions with improved prompts
• Adding solutions to posts that were created without AI keys

AI Models

• gemini-3-flash-preview

Supported Programming Languages

All 19 languages supported by LeetCode:

1. C++
2. Java
3. Python
4. Python3
5. C
6. C#
7. JavaScript
8. TypeScript
9. PHP
10. Swift
11. Kotlin
12. Dart
13. Go
14. Ruby
15. Scala
16. Rust
17. Racket
18. Erlang
19. Elixir

Local Development

Prerequisites

• Ruby (>= 2.7)
• Bundler
• Python (>= 3.8)

Running Locally

# Install Ruby dependencies
bundle install

# Serve the site locally
bundle exec jekyll serve

# Visit http://localhost:4000

Testing the Scripts

# Install Python dependencies
pip install -r scripts/requirements.txt

# Generate post for today
export GEMINI_API_KEY="your-key"
python scripts/generate_posts.py 2025-11-23

# Generate for date range
python scripts/generate_posts.py 2025-11-01 2025-11-10

Customization

Modify Posting Schedule

Edit .github/workflows/leetcode-daily.yml:

schedule:
  - cron: '0 0 * * *'  # Change this cron expression

Current: 00:00 UTC (midnight UTC)

Customize Theme

The site uses the Minima theme with heavy customizations:

• Override styles in _sass/ directory
• Modify layouts in _layouts/
• Update _config.yml for site settings

Troubleshooting

Posts Not Appearing

1. Check GitHub Actions logs for errors
2. Ensure workflow has write permissions
3. Verify _posts/_daily/ directory has new files

Build Failures

1. Check Jekyll build logs in Actions
2. Validate markdown frontmatter format
3. Ensure all required gems are in Gemfile

AI Solutions Missing

1. Verify API keys are added to GitHub Secrets
2. Check API key name: GEMINI_API_KEY
3. Check API rate limits (free tier has limits)

Cache Issues

If you're having trouble with problem fetching:

# Delete cache to force refresh
rm data/daily_challenges.json

Advanced Usage

Batch Generation

Generate posts for multiple dates:

# Generate all posts for November 2025
python scripts/generate_posts.py 2025-11-01 2025-11-30

Note: This will make many API calls. Use delays between requests to avoid rate limiting.

Caching System

The system caches daily challenge mappings in data/daily_challenges.json.

This cache allows fast regeneration without repeated API calls. The cache is automatically updated when generating posts for missing dates.

Contributing

Issues and pull requests are welcome!

Development Workflow

This project uses Git Flow branching strategy:

• master: Production, deployed to GitHub Pages
• develop: Main development branch
• develop-feature-{name}-{id}: Individual feature branches

See BRANCHING_STRATEGY.md for details.

License

MIT License - Feel free to use this for your own LeetCode blog!

Acknowledgments

• LeetCode for providing the daily challenge problems
• Google for Gemini API
• Gemini API for solution generation
• Jekyll and Minima theme

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For detailed developer documentation, see CLAUDE.md.