Day 22: Monkey Market
Megathread guidelines
- Keep top level comments as only solutions, if you want to say something other than a solution put it in a new post. (replies to comments can be whatever)
- You can send code in code blocks by using three backticks, the code, and then three backticks or use something such as https://topaz.github.io/paste/ if you prefer sending it through a URL
FAQ
- What is this?: Here is a post with a large amount of details: https://programming.dev/post/6637268
- Where do I participate?: https://adventofcode.com/
- Is there a leaderboard for the community?: We have a programming.dev leaderboard with the info on how to join in this post: https://programming.dev/post/6631465
Haskell
solution
import Control.Arrow import Data.Bits import Data.List import qualified Data.Map as M parse = fmap (secretNums . read) . lines secretNums :: Int -> [Int] secretNums = take 2001 . iterate (step1 >>> step2 >>> step3) where step1 n = ((n `shiftL` 06) `xor` n) .&. 0xFFFFFF step2 n = ((n `shiftR` 05) `xor` n) .&. 0xFFFFFF step3 n = ((n `shiftL` 11) `xor` n) .&. 0xFFFFFF part1 = sum . fmap last part2 = maximum . M.elems . M.unionsWith (+) . fmap (deltas . fmap (`mod` 10)) deltas l = M.fromListWith (\n p -> p) $ flip zip (drop 4 l) $ zip4 diffs (tail diffs) (drop 2 diffs) (drop 3 diffs) where diffs = zipWith (-) (tail l) l main = getContents >>= print . (part1 &&& part2) . parse