🎄 Advent of Code 2024 📅

My attempt at Advent of Code 2024, brushing up on Kotlin while at it

Disclaimer: input.txt(s) have been omitted as I was made aware that they are not to be publicly shared.

Table of Contents

• Overview
• Setup
  • Prerequisites
  • Session Cookies
    • Firefox
    • Chrome
  • Generating a New Day
• Running Code
  • Testing

Overview

Day	Name	Stars
01	Historian Hysteria	⭐ ⭐
02	Red-Nosed Reports	⭐ ⭐
03	Mull It Over	⭐ ⭐
04	Ceres Search	⭐ ⭐
05	Print Queue	⭐ ⭐
06	Guard Gallivant	⭐ ⭐
07	Bridge Repair	⭐ ⭐
08	Resonant Collinearity	⭐ ⭐
09	Disk Fragmenter	⭐ ⭐
10	Hoof It	⭐ ⭐
11	Plutonian Pebbles	⭐ ⭐
12	Garden Groups	⭐ ⭐
13	Claw Contraption	⭐ ⭐
14	Restroom Redoubt	⭐ ⭐
15
16
17
18
19
20
21
22
23
24
25

Setup

Prerequisites

I solved all of this year's problems in Kotlin. To get started, you'll need to follow the respective installation instructions:

• JDK 21 or later (use your favorite package manager to do so)
• Kotlin 2.1 or later
• Gradle 8.11 or later

Git Hooks

This project uses Git hooks to ensure code quality. To install the hooks:

# Make the install script executable
chmod +x setup/install-hooks.sh

# Install the hooks
./setup/install-hooks.sh

The pre-commit hook will:

1. Format all Kotlin files using ktlint
2. Run all tests
3. Prevent commit if either step fails
4. Show modified files if formatting changed anything

🍪 Session Cookies

The new_day.sh script uses Advent of Code's authentication session cookie to auto-fetch the day's input for the current year.

To get your own cookie, visit Advent of Code. Once logged in:

Firefox

• Right-click and select "Inspect". In the "Storage" tab, expand "Cookies" and select https://adventofcode.com. Copy the cookie titled "session"

Chrome

• Right-click and select "Inspect Element". In the "Application" tab, under "Storage", expand "Cookies" and select https://adventofcode.com. Copy the cookie titled "session"

Paste your session cookie data into a newly created .env file. (.env.example provides a structural example)

📆 Generating a New Day

• Add your Advent of Code session cookie to the .env file.

• Option 1: Run new_day.sh to create the current day's directory

• Option 2: Run new_day.sh d where d is a day between 1 - 25 to create that day's directory for the current year (if it doesn't already exist)

• Option 3: Run new_day.sh yyyy d where yyyy is a 4-digit year between 2015 and the current year, d is a day between 1 - 25 to create that date's directory (if it doesn't already exist)

• Navigate to the generated day's directory, equipped with the day's input and some boilerplate Kotlin files

Important

This script was only intended to be run during the duration of Advent of Code (i.e. Dec 1 through 25 of a given year).

Running Code

To run the code for day d, execute the following, replacing <d> with the specific day (e.g. 1 - 25)

# Run a specific day
./gradlew day -Pyear=2024 -Pday=1

# For single-digit days, both formats work:
./gradlew day -Pyear=2024 -Pday=1
./gradlew day -Pyear=2024 -Pday=01

Testing

Solutions are verified against known answers using JUnit tests. To run tests:

./gradlew test              # Run all tests
./gradlew test --tests "2024.day01.*"  # Run specific day's tests