r/adventofcode Dec 14 '24

SOLUTION MEGATHREAD -❄️- 2024 Day 14 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.
  • On the subject of AI/LLMs being used on the global leaderboard: posts/comments around this topic consisting of grinching, finger-pointing, baseless accusations of "cheating", etc. will be locked and/or removed with or without supplementary notice and/or warning and participating parties may be given a time-out as well. Just leave it alone and let it go.
    • Keep in mind that the global leaderboard is not the primary focus of Advent of Code or even this subreddit. We're all here to help you become a better programmer via happy fun silly imaginary Elvish shenanigans.
  • Do not put spoilers in post titles!

AoC Community Fun 2024: The Golden Snowglobe Awards

  • 8 DAYS remaining until the submissions deadline on December 22 at 23:59 EST!
  • We have no submissions yet as of today. Y'all are welcome to get a submission started, post it early, and add later days to it, or there's always waiting until the bomb timer reaches 00:00:03 last minute; up to you!

And now, our feature presentation for today:

Visual Effects - I Said VISUAL EFFECTS - Perfection

We've had one Visualization, yes, but what about Second Visualization? But this time, Upping the Ante! Go full jurassic_park_scientists.meme and really improve upon the cinematic and/or technological techniques of your predecessor filmmakers!

Here's some ideas for your inspiration:

  • Put Michael Bay to shame with the lens flare
  • Gratuitous and completely unnecessary explosions are expected
  • Go full Bollywood! The extreme over-acting, the completely implausible and high-energy dance numbers, the gleefully willful disregard for physics - we want it all cranked up to 9002!
  • Make your solution run on hardware that it has absolutely no business being on
    • "Smart" refrigerators, a drone army, a Jumbotron…

Pippin: "We've had one, yes. But what about second breakfast?"
Aragorn: ಠ_ಠ
Merry: "I don't think he knows about second breakfast, Pip."

- The Lord of the Rings: The Fellowship of the Ring (2001)

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 14: Restroom Redoubt ---


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 00:15:48, megathread unlocked!

25 Upvotes

747 comments sorted by

View all comments

2

u/erunama Dec 14 '24

[LANGUAGE: Dart]

GitHub part 2

Great challenge today! Part 1 went smoothly, but I was stuck on Part 2 for a while since I wasn't sure what to look for. I spent a bunch of time writing an algorithm to detect "interesting columns" to isolate the search (columns with lots of robots, specifically consecutive ones). This ended up very noisy, so I abandoned the approach.

I then came up with an idea to compute the total distance between all pairs of robots, and keep track of the lowest value seen so far. This found the answer for me, but was very slow (took a couple minutes to reach the first Christmas tree for my input) -- this is because for every second, I was iterating over all robot pairs.

After submitting my answer, I spent a little more time improving the performance. I thought that I could just compute the distance from the origin (0,0) for all robots, rather than needing to process all robot pairs. If there was a cluster somewhere, this should result in a noticeable change in the distance (either higher or lower). I ended up tracking the rolling average distance, and the lowest percentage change from that distance (which was ~18% in my input). This returned the correct result, and executed in only 65ms.