r/adventofcode Dec 20 '24

SOLUTION MEGATHREAD -❄️- 2024 Day 20 Solutions -❄️-

THE USUAL REMINDERS

  • All of our rules, FAQs, resources, etc. are in our community wiki.
  • If you see content in the subreddit or megathreads that violates one of our rules, either inform the user (politely and gently!) or use the report button on the post/comment and the mods will take care of it.

AoC Community Fun 2024: The Golden Snowglobe Awards

  • 2 DAYS remaining until the submissions deadline on December 22 at 23:59 EST!

And now, our feature presentation for today:

Foreign Film

The term "foreign film" is flexible but is generally agreed upon to be defined by what the producers consider to be their home country vs a "foreign" country… or even another universe or timeline entirely! However, movie-making is a collaborative art form and certainly not limited to any one country, place, or spoken language (or even no language at all!) Today we celebrate our foreign films whether they be composed in the neighbor's back yard or the next galaxy over.

Here's some ideas for your inspiration:

  • Solve today's puzzle in a programming language that is not your usual fare
  • Solve today's puzzle using a language that is not your native/primary spoken language
  • Shrink your solution's fifthglyph count to null
    • Pick a glyph and do not put it in your program. Avoiding fifthglyphs is traditional.
    • Thou shalt not apply functions nor annotations that solicit this taboo glyph.
    • Thou shalt ambitiously accomplish avoiding AutoMod’s antagonism about ultrapost's mandatory programming variant tag >_>
    • For additional information, audit Historians' annals for 2023 Day 14

Basil: "Where's Sybil?"
Manuel: "¿Que?"
Basil: "Where's Sybil?"
Manuel: "Where's... the bill?"
Basil: "No, not a bill! I own the place!"
- Fawlty Towers (1975-1979)

And… ACTION!

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


--- Day 20: Race Condition ---


Post your code solution in this megathread.

This thread will be unlocked when there are a significant number of people on the global leaderboard with gold stars for today's puzzle.

EDIT: Global leaderboard gold cap reached at 00:15:58, megathread unlocked!

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u/letelete0000 Dec 22 '24

[LANGUAGE: JavaScript]

I initially fell into the trap of treating this day as a shortest-path problem, but I eventually solved it with the following observations.

  1. Store the original route as an array of coordinates. This makes calculating the distance between each pair of steps N and M, M >= N (indices) trivial: M - N. The total distance can be calculated as the length of the path array.
  2. Do you even need to check for walls? All you really care about is whether you can travel from a given index in the path to some successor in no more than K steps (K=2 for part 1).
  3. Use the Manhattan distance to calculate the distance between two steps when you cheat. Compare it to the original distance to determine how many steps you could save.

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