Advent of Code 2021

Advent of Code is an Advent calendar of small programming puzzles for a variety of skill sets and skill levels that can be solved in any programming language you like.

This repo contains my solutions for this year's Advent of Code problem sets, written in Go. No one-liners here—we're doing this the hard way! I've organized each day's problem sets into Go modules and wrote a simple runner in main.go to quickly iterate on the solutions.

I haven't used Go in a while, so I'm relearning the module system. I have a feeling that this project can be better organized. Suggestions are welcome :).

I've also included unit tests which run on every git push via GitHub Actions—this makes the badge above all nice and green.

Howto

Each day has an associated problem set. Use make init to generate all the required files for each day. For example:
```
make init FOLDER=day3
```
Add new case statements in main.go.
Start writing code in the ${DAY} folder.

When you're ready to test, add unit tests in the ${DAY} folder. Use day1/part2_test.go as a template, and add a line to the test rule in Makefile. Afterwards, run tests with make test. E.g.:

$ make test
go test github.com/dlo/aoc2021/day1 -cover
ok      github.com/dlo/aoc2021/day1     0.234s  coverage: 100.0% of statements
go test github.com/dlo/aoc2021/utils -cover
ok      github.com/dlo/aoc2021/utils    (cached)        coverage: 12.1% of statements

Run the command for a specific day:

$ go build
$ ./aoc2021 --day 1 --part 1 --filename input.txt // Reads from day01/testdata/input.txt