Advent of Code 2021

Solutions to the 2021 edition of Advent of Code in Swift.

Day 0

Spent some time figuring out a good way to do this in Swift without having to manage a bunch of Xcode projects/targets and still have the ability to use external dependencies using the Swift Package Manager.

I chose the excellent swift-sh to make it easy to run/compile standalone scripts with external dependencies (such as swift-algorithms).

Day 1: Sonar Sweep

Used a couple of helpful functions from swift-algorithms to massage and process the data without writing a bunch of boilerplate.

Day 2: Dive!

Fairly straightforward, started with a quick 'n dirty solution, later changed it to use a bit more functional approach using map/reduce and avoiding local state/side effects.

Day 3: Binary Diagnostic

A broken dishwasher limited the time I had availble to spend on this, hence the copiuous duplication in part 2.

Day 4: Giant Squid

Trickiest part was to figure out the correct halting condition in part 2. Much love for Swift's typealias so I don't have to mentally deal with types like [[[Int]]].

Day 5: Hydrothermal Venture

TIL: signum() is awesome. In the end part 2 is actually cleaner than part 1. I could have just used that with the additional constraint of filtering out diagonals for part 1.