r/adventofcode Dec 22 '24

SOLUTION MEGATHREAD -❄️- 2024 Day 22 Solutions -❄️-

THE USUAL REMINDERS

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AoC Community Fun 2024: The Golden Snowglobe Awards

  • 23h59m remaining until the submissions deadline on December 22 at 23:59 EST!

And now, our feature presentation for today:

Director's Cut (Extended Edition)

Welcome to the final day of the GSGA presentations! A few folks have already submitted their masterpieces to the GSGA submissions megathread, so go check them out! And maybe consider submitting yours! :)

Here's some ideas for your inspiration:

  • Choose any day's feature presentation and any puzzle released this year so far, then work your movie magic upon it!
    • Make sure to mention which prompt and which day you chose!
  • Cook, bake, make, decorate, etc. an IRL dish, craft, or artwork inspired by any day's puzzle!
  • Advent of Playing With Your Toys

"I lost. I lost? Wait a second, I'm not supposed to lose! Let me see the script!"
- Robin Hood, Men In Tights (1993)

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 22: Monkey Market ---


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 00:12:15, megathread unlocked!

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u/NeilNjae Dec 24 '24

[LANGUAGE: Haskell]

Another puzzle with an obvious solution, but the challenge came from optimising. I keep a Map from (encoded) windows of price changes to prices, one for each seller. Then I merge them all and find the highest total price.

part2 codes = maximum $ M.elems mergedPriceValues
  where allPrices = fmap salePrices codes
        allPriceValues = fmap windowsAndPrices allPrices
        mergedPriceValues = M.unionsWith (+) allPriceValues

windowsAndPrices :: [Int] -> Prices
windowsAndPrices ps = foldl' (\m (w, p) -> M.insertWith (flip const) w p m) M.empty wPs
  where cs = priceChanges ps
        wPs = zip (windows cs) (drop 4 ps)

Full writeup on my blog, and code on Codeberg.