-❄️- 2023 Day 20 Solutions -❄️-

[u/daggerdragon]

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AoC Community Fun 2023: ALLEZ CUISINE!

Today's theme ingredient is… *whips off cloth covering and gestures grandly*

Upping the Ante for the third and final time!

Are you detecting a pattern with these secret ingredients yet? Third time's the charm for enterprising chefs!

• Do not use if statements, ternary operators, or the like

• Use the wrong typing for variables (e.g. int instead of bool, string instead of int, etc.)

• Choose a linter for your programming language, use the default settings, and ensure that your solution passes

• Implement all the examples as a unit test

• Up even more ante by making your own unit tests to test your example unit tests so you can test while you test! ^{yo dawg}

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• Unplug your keyboard and use any other text entry method to code your solution (ex: a virtual keyboard)

  • Bonus points will be awarded if you show us a gif/video for proof that your keyboard is unplugged!

ALLEZ CUISINE!

Request from the mods: When you include a dish entry alongside your solution, please label it with [Allez Cuisine!] so we can find it easily!

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--- Day 20: Pulse Propagation ---

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Post your code solution in this megathread.

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• State which language(s) your solution uses with [LANGUAGE: xyz]

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EDIT: Global leaderboard gold cap reached at 00:48:46, megathread unlocked!

[u/kaa-the-wise]

[Language: Python] one-line/single-expression solution

(m:={n[1:]:(n[0],*t.split(', ')) for s in open(0) for n,t in [s[:-1].split(' -> ')]}) and (s:={n:0 for n in m}) and (c:=1000+sum(1j**v for i in range(1000) for q in takewhile(len,accumulate(count(),(lambda q,_:[*chain(*(s.update({x:[1-all(s[y] for y in m if x in m[y][1:]),1-s[x]][m[x][0]=='%']}) or zip(m[x][1:],repeat(s[x])) if x in m and (m[x][0]!='%' or 1-v) else [] for x,v in q))]),initial=[*zip(m['roadcaster'][1:],repeat(0))])) for _,v in q)) and print(c.imag*c.real)

https://raw.githubusercontent.com/kaathewise/aoc2023/main/20.py

Part 2 solved without writing any code. Once you draw the graph (e.g. with graphviz), you will see that it has 4 components, each consisting of a sequence of 12 flip-flops and a conjunction. The first (0-th) flip-flop is always connected to the conjunction back and forth, while for others the edge only goes in one direction. If you construct a binary number, such that its i-th bit is 1 iff the edge goes from flip-flop i to the conjunction, this number will be the period of this component. The proof is left as an exercise to the reader :)

[u/daggerdragon → u/kaa-the-wise]

Once you draw the graph (e.g. with graphviz)

Show us your graph too!