Advent of Code 2025 – Emacs Lisp Solutions

This repository contains my solutions for Advent of Code 2025, implemented in Emacs Lisp. The goal is to solve the daily programming puzzles while learning and improving my Emacs Lisp skills.

About Advent of Code

Advent of Code is an annual series of programming puzzles created by Eric Wastl. Each day from December 1st to 25th, a new puzzle is released, challenging participants with algorithmic and logical problems. Huge thanks to Eric for creating and maintaining this wonderful event!

Why Emacs Lisp?

I’m using this as an opportunity to:

• Deepen my understanding of Emacs Lisp
• Explore functional programming patterns in a Lisp environment
• Integrate puzzle-solving directly into my Emacs workflow

How to Run

1. Open any solution.el file in Emacs.
2. Evaluate the buffer (M-x eval-buffer).
3. Call the main solving function, e.g., (day-01-part-1).

Alternatively, use M-x ielm or M-x eval-expression to run functions interactively.

Repository Structure

advent-of-code-2025/
├── README.md
├── init.el
├── utils
│   └── common.el
├── day-01/
│    └──  solution.el
├── day-02/
│    └── solution.el
└── ...

Each day’s directory contains:

• solution.el: The Emacs Lisp code solving the puzzle
• input.txt: My personalized puzzle input (not shared publicly)

Learning Resources

• Advent of Code 2025 – The official puzzle site
• GNU Emacs Lisp Reference Manual – Comprehensive Emacs Lisp documentation
• An Introduction to Programming in Emacs Lisp – Great for beginners

Notes

• Solutions are written for clarity and learning, not necessarily for optimal performance.
• Input files are excluded via .gitignore to respect Advent of Code guidelines.
• Feedback and suggestions are welcome, especially regarding Emacs Lisp best practices!

Happy hacking, and may your Emacs sessions be ever productive!