Advent of Code day 14

Day 13 does not exist. we do not speak of it. (at some point I'll circle back around, but that point is not now. if you want a nice answer, check out my friend Dave's solution here: (https://github.com/davedelong/AOC/blob/main/Sources/AOC2022/Day%2013/2022-Day13.swift)

Day 14, however, DOES exist, and I blasted through it in just slightly under 1:10! :) I did hit an interesting swift-specific thing, which I'll share below the fold, along w/ the bits I thought were most interesting/relevant/etc. It was a very long day, and I am very tired for it being 10 PM so, forgive me in advance.

Ok, so, I'm writing/coding/working on an M1 Macbook Air running Monterey. (aka macOS 12.6). (this is relevant)

So, I went to write my parsing code, and the inputs are sets of coordinates, separated by the string " -> ", and I wanted to pull those out to get just the coordinates. This is pretty basic input parsing, and thankfully there's a method on that! it's actually on StringProtocol, and it looks like this:

func split(separator: Self.Element, maxSplits: Int = Int.max, omittingEmptySubsequences: Bool = true) -> [Self.SubSequence]

and I have been using it pretty consistently all month. Today, however, I went to use it like so:

line.split(separator: " -> ")

and the nice compiler informed me that that api required macOS 13, and I was set up to support 12.6, so I needed to gate it with an #available or similar. So, I looked at the API again. And again. and it kept saying "requires macOS 10.10+".

I asked the dev chat I frequent if anyone had any ideas, and my day-job-boss suggested a completely different api (which I have feelings about the divergent names, but another day), components(separatedBy:), but the argument for that is a CharacterSet, ie: please split on any of these single characters.

And that's what triggered my brain to actually READ that method declaration again. It's defined on StringProtocol, like I said, so it doesn't talk about what a Self is or a Self.Element, but on String, Self is obviously the String struct, and Element is the type of thing they're built out of... Characters. Which, fuuuck. -> is absolutely NOT a Character.

Turns out, there's a NEW split api in macOS 13 that takes a String as the separator, and that's the one I was invoking. Oops!

My vengeful solution:

var coords = line.split(separator: " ")
coords.removeAll { substr in
    substr == "->"
}

The actual solution was pretty simple. I'm proud of my Room class to wrap it all together, and my re-use and extension of Coord was pretty slick:

extension Coord {
    func coordBelow() -> Coord {
        return Coord(x: x, y: y + 1)
    }

    func coordDownLeft() -> Coord {
        return Coord(x: x - 1, y: y + 1)
    }

    func coordDownRight() -> Coord {
        return Coord(x: x + 1, y: y + 1)
    }
}

The one gotcha I found was that I assumed my coordinate pairs were in increasing order, and that was Not True, so I had to check to make sure my ClosedRanges were increasing, as the Swift Gods decree. :)

you can see the rest here: (https://github.com/nothes/AdventOfCode/blob/main/AoC/AoC/Day%2014/day14.swift)

Rey

@nothe

She's a Nerd!

Advent of Code day 14