Advent of Code 🎄

This repository contains my own solutions for the Advent of Code, as well as some utilities for creating and working on challenges, and helper functions for input parsing.

Requirements

Nix & NixOS

A flake.nix is available. You can run

nix develop

to enter a dev shell with cargo and all the necessary libraries.

Alternatively, for systems without flake, a shell.nix is available, so you should be able to run this:

nix-shell

There is also an .envrc available for direnv users. Allowing the directory should put you in a development shell.

Others

You will need to have Rust installed. No other dependecy needed. This should work on most systems.

How to use

The first thing to do is to create a file named .aoc-token that contains your session token for Advent of Code. This will allow the program to fetch problem inputs from the Advent of Code website. In order to get your session token:

1. Go to a past year problem's input (for example, https://adventofcode.com/2022/day/1/input) while logged in.
2. Open the web inspector (usually with F12 on Firefox, no idea for other browsers. You're doing AoC, you can figure that out yourself).
3. Go to the "network" tab and look for the GET request for the input file (you may have to reload).
4. In the headers, find the Cookie header. It should have a value that looks like session=.... Copy the entire string (including "session=") into the .aoc-token file.

There are two main crates that are distinct from the solution crates:

• aoc-manager is a utility binary that allows you to create a new crate for a given day and year, and to watch for changes in a solution crate and compile and run every time a change is detected.
• aoc-utils is a helper library that contains useful functions to quickly parse AoC input into different formats. This is mainly here to save time when working on the day's problem, and "refined" solutions should just write the parsing in the solution, without relying on this crate.

If the current date is an Advent of Code day, i.e. between December 1st and December 25th of the current year, inclusive, then you can run:

cargo run -- add

To quickly create a crate for the day's problem, add it to the workspace, and begin to watch the sources for changes.

If you want to begin working on a previous day's challenge, you can run:

# For a day in the current year's Advent of Code
cargo run -- add -d my-day
# For a day in a specific year of Advent of Code
cargo run -- add -d my-day -y my-year

All of these commands will do the following:

• Create the crate day_<year>_<day>, with a code skeleton specifically made for an AoC problem
• Add this crate to the workspace in Cargo.toml
• Fetch the problem's input from the Advent of Code website, and cache it in the .input-cache directory (so that deleting and re-creating the crate doesn't make too many requests to AoC).
• Begin watching for changes on that crate's main.rs file, and trigger a cargo run for that crate for every change made.

If you only want to watch an already existing day, you can run the following:

cargo run -- watch -d my-day -y my-year

And if you want to run the standalone solution yourself, you can just specify the binary when using cargo run, just like in a normal workspace:

cargo run --bin day_my-day_my-year

If you don't have the input already fetched (for example, you just cloned this repository), you can run the following command, assuming you set up your AoC token as explained before:

cargo run -- fetch