If you're writing Advent of Code solutions in Rust, then I've written a crate that can fetch the user input data directly from the main website.

Long story short, you provide it a login token copied from your browser cookies, and it can fetch the input data by year and day. Inputs are cached locally, so it'll only download it once for a given problem. This was heavily inspired by the PyPi advent-of-code-data package.

Unlike other AoC-centric Rust crates, that's all it does. The other crates I've seen all want the code structured in a specific way to add timing benchmarks, unit testing, and other features. I wanted something lightweight where you just call a function to get the input; no more and no less.

To use the crate:

• Follow the AoCD instructions to set the AOC_SESSION environment variable.
  This key is used for authentication and should not be shared with anyone.
• Add the aocfetch crate to your Cargo.toml [dependencies] section:
  aocfetch = { git = "https://github.com/ooterness/AdventOfCode.git" }
• Import the crate and call aocfetch::get_data(year, day) to fetch your input data.

An example:

use aocfetch;

fn main() {
    let input = aocfetch::get_data(2023, 1).unwrap();
    println!("My input data: {}", input);
    println!("Part 1 solution: 42");    // TODO
    println!("Part 2 solution: 42");    // TODO
}

If this goes well I will submit it to crates.io, but I wanted to open this up for beta-testing first.