aocgl

Advent of Code solutions written in Gleam. Browse the solution wiki for tag/difficulty indexes, or see per-year pages in each src/year_XXXX/ folder.

Stats

45 problems solved across 11 years — Tags · Difficulty · Benchmarks

Years: 2015 | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025

Day	2015	2016	2017	2018	2019	2020	2021	2022	2023	2024	2025
1	⭐	⭐	⭐	⭐	⭐	⭐	⭐	⭐	⭐	⭐	⭐
2	⭐	⭐	⭐	⭐		⭐		⭐
3	⭐	⭐				⭐
4	⭐					⭐
5						⭐				⭐
6					⭐	⭐
7				⭐		⭐				⭐
8
9
10									⭐
11
12			⭐				⭐	⭐
13		⭐
14
15							⭐
16								⭐
17									⭐
18					⭐					⭐
19
20
21
22
23									⭐	⭐
24		⭐						⭐
25				⭐					⭐

🏷️ Tags

graph 21 grid 7 shortest-path 7 bfs 6 implicit-graph 6 bitmask 3 dfs 3 set 3 brute-force 2 dijkstra 2 geometry 2 reduction 2 regex 2 scc 2 sort 2 topological-sort 2 arithmetic 1 backtracking 1 bron-kerbosch 1 circular-list 1 clique 1 encode 1 floyd-warshall 1 hash 1 linear-scan 1 linked-list 1 longest-path 1 min-cut 1 modular-algebra 1 n-sum 1 over-engineered 1 simulation 1 state-space-search 1 stoer-wagner 1 top-k 1 transpose 1 tree 1 tsp 1 validation 1 window 1

Getting Started

Prerequisites

• Gleam installed

Installation

gleam deps download

Setting up AOC Session Key (Optional)

To automatically fetch puzzle inputs, you can set your Advent of Code session key:

export AOC_SESSION_KEY=your_session_key_here

Without this key, the scaffold tool will create an empty input file that you'll need to fill manually.

Usage

Running Solutions

Run a specific day's solution:

gleam run -- --year <year> --day <day>

Examples:

gleam run -- --year 2024 --day 1      # Run 2024 Day 1
gleam run -- --year 2023 --day 25     # Run 2023 Day 25

Scaffolding a New Solution

Generate the boilerplate for a new day:

gleam run -m scripts/scaffold -- --year <year> --day <day>

Examples:

gleam run -m scripts/scaffold -- --year 2024 --day 1
gleam run -m scripts/scaffold -- --year 2023 --day 15

This will create:

• src/year_YYYY/day_DD.gleam - Solution module with template code
• test/year_YYYY/day_DD_test.gleam - Test module
• inputs/YYYY_DD.txt - Input file (auto-fetched if AOC_SESSION_KEY is set)

The scaffold tool will:

• Create necessary directories if they don't exist
• Skip files that already exist (safe to re-run)
• Fetch your personal puzzle input from adventofcode.com (if session key is provided)

Running Tests

gleam test                    # Run all tests

Project Structure

aocgl/
├── src/
│   ├── aocgl.gleam           # Main entry point
│   ├── common/               # Shared utilities
│   ├── scripts/
│   │   └── scaffold.gleam    # Scaffolding tool
│   └── year_YYYY/            # Solutions by year
│       ├── runner.gleam      # Year-specific router
│       └── day_DD.gleam      # Individual day solutions
├── test/
│   └── year_YYYY/
│       └── day_DD_test.gleam # Tests for each day
└── inputs/
    └── YYYY_DD.txt           # Puzzle inputs

Solution Template

Each scaffolded solution follows this structure:

pub fn solve(raw_input: String) -> Solution {
  let input = parse(raw_input)
  let part_1 = solve_part_1(input) |> OfInt
  let part_2 = solve_part_2(input) |> OfInt

  Solution(part_1, part_2)
}

fn solve_part_1(input: List(Int)) -> Int {
  // Implement part 1 solution
  input |> list.length()
}

fn solve_part_2(input: List(Int)) -> Int {
  // Implement part 2 solution
  input |> list.length()
}

fn parse(raw_input: String) -> List(Int) {
  // Parse input into desired format
}

Please note that using list.length() and assuming this will be a Solution(OfInt, OfInt) was just me being lazy and since most of Advent of Code problems have List(Int) like expectations, I did it instead of todo-s - so that I can edit less.

Development

gleam run      # Run the project
gleam test     # Run the tests
gleam build    # Build the project

Every solution has its own main so that we can echo parts of it as we develop and run it with gleam run -m year_<year>/day_dd for quicker feedbacks.

Updating the Wiki

After solving a new puzzle, regenerate the wiki with:

python3 scripts/gen_wiki.py

This will rebuild wiki/Home.md, wiki/tags/, wiki/difficulty.md, and each src/year_XXXX/README.md from the /// Title/Link/Difficulty/Tags doc comments at the top of every solved day file. Then just commit the results.

Make sure your solution file starts with the standard header:

/// Title: Your Puzzle Title
/// Link: https://adventofcode.com/YYYY/day/DD
/// Difficulty: xs | s | m | l | xl
/// Tags: tag1 tag2 tag3

Contributing

Feel free to explore different approaches and optimizations for the solutions!

License

This project is for educational purposes and personal development.