🧠 LeetCode APL Solutions

LeetCode problems solved in APL (A Programming Language)

⚠️ AI-Generated Content Notice

This project was created with AI assistance. All APL solutions and explanations in this repository were generated using artificial intelligence. While efforts have been made to ensure code quality:

• Solutions may contain errors or non-optimal approaches
• Code has not been extensively tested in production APL interpreters
• Explanations are based on code analysis and may not reflect APL best practices
• This is primarily an educational/experimental project

Use at your own discretion. Contributions and corrections are welcome!

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🌍 Languages: English | 繁體中文 | 简体中文 | 日本語 | Español | Deutsch | Français

📚 Problems

View All 173 Problems

• 🟢 Easy: 70+
• 🟡 Medium: 50+
• 🔴 Hard: 10+

🚀 Quick Start

# Install APL
brew install gnu-apl  # macOS
apt install gnu-apl   # Linux

# Browse solutions
cd problems/001-two-sum
cat 001-two-sum.json

📖 Documentation

• Problem Index
• How to Add Problems
• Project Structure

ReverseList ← {⌽⍵}

Complexity: Time O(n), Space O(1)

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📂 Repository Structure

problems/
├── 001-two-sum/
│   ├── README.md           # English
│   ├── README.zh-CN.md     # 简体中文
│   ├── README.zh-TW.md     # 繁體中文
│   ├── README.ja.md        # 日本語
│   ├── README.es.md        # Español
│   ├── README.de.md        # Deutsch
│   └── README.fr.md        # Français
├── 136-single-number/
│   └── ... (7 language files)
└── 206-reverse-linked-list/
    └── ... (7 language files)

🌍 Multi-Language Support

This repository provides documentation in 7 languages:

Language	README
🇬🇧 English	README.md
🇹🇼 繁體中文	README.zh-TW.md
🇨🇳 简体中文	README.zh-CN.md
🇯🇵 日本語	README.ja.md
🇪🇸 Español	README.es.md
🇩🇪 Deutsch	README.de.md
🇫🇷 Français	README.fr.md

Each problem file in the problems/ directory also includes descriptions and explanations in all 7 languages.

🚀 Features

• ✅ 100+ Classic Problems: Comprehensive coverage of LeetCode's most important problems
• ✅ APL Solutions: Unique implementations using APL's powerful array operations
• ✅ Detailed Explanations: Each solution includes complexity analysis and explanations
• ✅ 7 Languages: Full documentation in English, 繁中, 简中, 日本語, Español, Deutsch, Français
• ✅ Modular Structure: Each problem in its own JSON file for easy navigation
• ✅ Educational Focus: Learn array programming through practical examples
• ✅ Open Source: MIT licensed, contributions welcome

📖 Example Solutions

Problem 1: Two Sum

TwoSum ← {
    ⍝ ⍺: target sum, ⍵: array
    indices ← ⍸⍺=+/∘.,⍨⍵
    2↑indices
}

⍝ Usage
target ← 9
nums ← 2 7 11 15
result ← target TwoSum nums  ⍝ Returns: 0 1

Explanation: Uses outer product ∘. to generate all possible pair sums, then ⍸ to find matching indices.

• Time Complexity: O(n²)
• Space Complexity: O(n²)

Problem 136: Single Number

SingleNumber ← {≠/⍵}

⍝ Usage
nums ← 4 1 2 1 2
result ← SingleNumber nums  ⍝ Returns: 4

Explanation: XOR reduce - APL's ≠ is XOR, / is reduce. Elegant one-liner leveraging XOR properties.

• Time Complexity: O(n)
• Space Complexity: O(1)

Problem 206: Reverse Linked List

ReverseList ← {⌽⍵}

⍝ Usage
list ← 1 2 3 4 5
result ← ReverseList list  ⍝ Returns: 5 4 3 2 1

Explanation: ⌽ is APL's reverse operator - the simplest possible solution!

• Time Complexity: O(n)
• Space Complexity: O(1)

🛠️ Technology Stack

• Language: APL (A Programming Language)
• Documentation: Pure Markdown (Static)
• Format: JSON data + Markdown READMEs
• i18n: 7 languages (English, 简中, 繁中, 日本語, Español, Deutsch, Français)
• Hosting: GitHub (static files)

📂 Project Structure

leetcode-apl-solutions/
├── problems/                    # All problem solutions
│   ├── 001-two-sum/            # Each problem in its own directory
│   │   ├── README.md           # 7 language versions
│   │   ├── README.zh-CN.md
│   │   └── ...
│   ├── 136-single-number/
│   ├── 206-reverse-linked-list/
│   └── index.json              # Problem metadata
├── PROBLEMS_INDEX.md           # Complete problem list (7 languages)
├── PROBLEMS_INDEX.zh-CN.md
├── README.md                   # Main documentation (7 languages)
├── README.zh-CN.md
└── generate_static_readmes.py  # Generator script

💻 How to Use

🌐 Browse on GitHub

Simply browse this repository on GitHub! No server needed - everything is static Markdown files.

1. Start here: PROBLEMS_INDEX.md - Complete list of all problems
2. Click any problem to view its full solution with explanation
3. Switch languages using the navigation bar at the top of each page

📥 Clone Locally

git clone https://github.com/wmh/leetcode-apl-solutions.git
cd leetcode-apl-solutions

# View complete problem list
cat PROBLEMS_INDEX.md

# Browse a specific problem
cat problems/001-two-sum/README.md

# View in Chinese
cat problems/001-two-sum/README.zh-CN.md

🔧 Try the APL Solutions

To actually run the APL code, you'll need an APL interpreter:

1. Online (easiest): Visit TryAPL.org
2. Dyalog APL: Download from dyalog.com
3. GNU APL:
   • Linux: apt install gnu-apl
   • macOS: brew install gnu-apl

🔄 Generate More Problems

Use the included generator script to create new problem READMEs:

# Add your problem data to problems/*.json
# Then regenerate all READMEs
python3 generate_static_readmes.py

🤝 Contributing

Contributions are welcome! Here's how you can help:

1. Add More Problems: Implement additional LeetCode problems in APL
2. Improve Solutions: Optimize existing APL solutions
3. Fix Bugs: Report and fix any issues you find
4. Translations: Help improve language translations
5. Documentation: Enhance problem explanations

📘 Contribution Guide

See HOW_TO_ADD_PROBLEMS.md for detailed instructions on adding new problems.

Quick steps:

1. Create a JSON file in problems/ with your solution
2. Run python3 generate_static_readmes.py
3. Commit and push your changes

Contribution Steps

1. Fork the repository
2. Create your feature branch (git checkout -b feature/AmazingFeature)
3. Commit your changes (git commit -m 'Add some AmazingFeature')
4. Push to the branch (git push origin feature/AmazingFeature)
5. Open a Pull Request

📚 Resources

Learn APL

• APL Wiki - Comprehensive APL documentation
• Dyalog APL Tutorial - Official Dyalog tutorial
• APL Cart - Searchable APL idioms
• Try APL - Online APL interpreter

LeetCode

• LeetCode Problems - Official problem list
• LeetCode Top Interview Questions

📜 License

This project is licensed under the MIT License - see the LICENSE file for details.

🙏 Acknowledgments

• Kenneth E. Iverson - Creator of APL
• LeetCode - For providing excellent algorithmic problems
• Dyalog Ltd - For maintaining and developing APL
• APL Community - For keeping this beautiful language alive

📧 Contact

• GitHub: @wmh
• Issues: Report issues or suggestions

⭐ Star History

If you find this project helpful, please consider giving it a star! ⭐

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Made with ❤️ and lots of ⍵, ⍺, ⌽, and ∇

"APL is a mistake, carried through to perfection. It is the language of the future for the programming techniques of the past: it creates a new generation of coding bums." - Edsger W. Dijkstra

"APL is like a perfect diamond: flawless, beautifully symmetrical, but you can't do anything with it." - Unknown

Despite the criticisms, APL remains one of the most elegant and powerful languages for array manipulation! 🎯