advent-of-code/README.md

<img src="./.assets/christmas_ferris.png" width="164" align="center">

# 🎄 [Advent of Code](https://adventofcode.com/)

![Language](https://badgen.net/badge/Language/Rust/orange)
[![CI](https://github.com/fspoettel/advent-of-code-rust/actions/workflows/ci.yml/badge.svg)](https://github.com/fspoettel/advent-of-code-rust/actions/workflows/ci.yml)

<!--- advent_readme_stars table --->

## Setup

### Create your _advent of code_ repository

1.  Open [the template repository](https://github.com/fspoettel/advent-of-code-rust) on Github.
2.  Click `Use this template` and create your repository.
3.  Clone your repository to your computer.

### Setup rust

1.  Install the [Rust toolchain](https://www.rust-lang.org/tools/install).
2.  (recommended) Install the [rust-analyzer](https://rust-analyzer.github.io/manual.html) extension for your code editor.
3.  (optional) Install a native debugger. If you are using VS Code, [CodeLLDB](https://marketplace.visualstudio.com/items?itemName=vadimcn.vscode-lldb) is a good option.

---

✨ You can start solving puzzles now! Head to the [Usage section](#usage) to see how to use this template. If you like, you can configure [some optional features](#optional-template-features).

## Usage

### Setup new day

```sh
# example: `./bin/scaffold 1`
./bin/scaffold <day>

# output:
# Created module "src/bin/01.rs"
# Created empty input file "src/inputs/01.txt"
# Created empty example file "src/examples/01.txt"
# ---
# 🎄 Type `cargo run --bin 01` to run your solution.
```

Individual solutions live in the `./src/bin/` directory as separate binaries.

Every [solution](https://github.com/fspoettel/advent-of-code-rust/blob/master/bin/scaffold#L21-L52) has _unit tests_ referencing its _example_ file. Use these unit tests to develop and debug your solution against example inputs. When editing a solution, `rust-analyzer` will display buttons for these actions above the unit tests.

### Download inputs for a day

> **Note**  
> This command requires configuring the optional [automatic input downloads](#automatic-input-downloads) feature.

```sh
# example: `./bin/download 1`
./bin/download <day>

# output:
# Loaded session cookie from "/home/felix/.adventofcode.session".
# Downloading input for day 1, 2021...
# Saving puzzle input to "/tmp/tmp.MBdcAdL9Iw/input"...
# Done!
# ---
# 🎄 Successfully wrote input to "src/inputs/01.txt"!
```

To download inputs for previous years, append the `--year` flag. _(example: `./bin/download 1 --year 2020`)_

Puzzle inputs are not checked into git. [See here](https://old.reddit.com/r/adventofcode/comments/k99rod/sharing_input_data_were_we_requested_not_to/gf2ukkf/?context=3) why.

### Run solutions for a day

```sh
# example: `cargo run --bin 01`
cargo run --bin <day>

# output:
#     Running `target/debug/01`
# 🎄 Part 1 🎄
#
# 6 (elapsed: 37.03µs)
#
# 🎄 Part 2 🎄
#
# 9 (elapsed: 33.18µs)
```

To run an optimized version for benchmarking, use the `--release` flag or the alias `cargo rr --bin <day>`.

Displayed _timings_ show the raw execution time of your solution w/o overhead (e.g. file reads).

### Run solutions for all days

```sh
cargo run

# output:
#     Running `target/release/aoc`
# ----------
# | Day 01 |
# ----------
# 🎄 Part 1 🎄
#
# 0 (elapsed: 170.00µs)
#
# 🎄 Part 2 🎄
#
# 0 (elapsed: 30.00µs)
# <...other days...>
# Total: 0.20ms
```

To run an optimized version for benchmarking, use the `--release` flag or the alias `cargo rr`.

_Total timing_ is computed from individual solution _timings_ and excludes as much overhead as possible.

### Run all solutions against example input

```sh
cargo test
```

### Format code

```sh
cargo fmt
```

### Lint code

```sh
cargo clippy
```

## Optional template features

### Automatic input downloads

Install [`aoc-cli`](https://github.com/scarvalhojr/aoc-cli/) and follow their setup instructions. Once installed, you can use the [download command](#download-inputs-for-a-day).

### Readme progress tracker

This template includes [a Github action](https://github.com/k2bd/advent-readme-stars) that automatically updates the readme with your advent of code progress.

To enable it, complete the following steps:

#### 1. Create private leaderboard

Go to the leaderboard page of the year you want to track and click _Private Leaderboard_. If you have not created a leaderboard yet, create one by clicking _Create It_. Your leaderboard should be accessible under `https://adventofcode.com/{year}/leaderboard/private/view/{aoc_user_id}`.

#### 2. Set repository secrets

Go to the _Secrets_ tab in your repository settings and create the following secrets:

-   `AOC_ENABLED`: This variable controls whether the workflow is enabled. Set it to `true` to enable the progress tracker.
-   `AOC_USER_ID`: Go to [this page](https://adventofcode.com/settings) and copy your user id. It's the number behind the `#` symbol in the first name option. Example: `3031`
-   `AOC_YEAR`: the year you want to track. Example: `2021`
-   `AOC_SESSION`: an active session for the advent of code website. To get this, press F12 anywhere on the Advent of Code website to open your browser developer tools. Look in your Cookies under the Application or Storage tab, and copy out the `session` cookie.

> **Note**  
> The session cookie might expire after a while (~1 month) which causes the automated workflow to fail. To fix this issue, refresh the `AOC_SESSION` secret.

### CI: enable clippy lints

Uncomment the `clippy` job in the `ci.yml` workflow to enable clippy checks in CI.

## Useful crates

-   [itertools](https://crates.io/crates/itertools): Extends iterators with extra methods and adaptors. Frequently useful for aoc puzzles.
-   [hashbrown](https://crates.io/crates/hashbrown): Faster hashing functions for `HashMap` and `HashSet`.

Do you have aoc-specific crate recommendations? [Share them!](https://github.com/fspoettel/advent-of-code-rust/edit/master/README.md)