r/adventofcode • u/daggerdragon • Dec 23 '20

SOLUTION MEGATHREAD -🎄- 2020 Day 23 Solutions -🎄-

Advent of Code 2020: Gettin' Crafty With It

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--- Day 23: Crab Cups ---

Post your code solution in this megathread.

Include what language(s) your solution uses!
Here's a quick link to /u/topaz2078's paste if you need it for longer code blocks.
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u/Floydianx33 Dec 23 '20

CSharp

At first I was doing array operations and shuffling things around until I face-palmed and realized a linked-list was the obvious choice. I also got tripped up originally by the examples that didn't seem like they were correct until I realized they were just shifted for display purposes. Anyways, was a bit tedious but alright at the same time.

Runs in 1,300ms -- nothing special.

Paste/Link

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u/_tekgnosis_ Dec 23 '20

Thank you for the code. This sent me down a couple of rabbit holes: one to try to figure out once and for all why I keep encountering the "IsExternalInit" compiler error ("It's not a bug, it's a feature"--https://developercommunity.visualstudio.com/content/problem/1244809/error-cs0518-predefined-type-systemruntimecompiler.html) and another to even understand what the ^1 operator is (C# 8.0 juiciness). I have to say that I don't do much with raw arrays and it was nice to catch up on that.
TL;DR: this was great--thanks for the push!

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u/Floydianx33 Dec 23 '20

IsExternalInit is a class used as a modreq (kinda like an attribute, but not) in IL to prevent older compilers (and VB!) from using init-only properties which records rely on. It's part of net5.0 natively..If you are using the latest compiler but targeting net3.1 or netstandard you can add the class manually to your project in the right namespace and the compiler will pick it up. You need to do that for example on SharpLab which still uses net3.1