import Data.Bits
import Data.List
import Data.Map (Map)
import Data.Map qualified as Map

next :: Int -> Int
next = flip (foldl' (\x n -> (x `xor` shift x n) .&. 0xFFFFFF)) [6, -5, 11]

bananaCounts :: Int -> Map [Int] Int
bananaCounts seed =
  let secrets = iterate next seed
      prices = map (`mod` 10) secrets
      changes = zipWith (-) (drop 1 prices) prices
      sequences = map (take 4) $ tails changes
   in Map.fromListWith (const id) $
        take 2000 (zip sequences (drop 4 prices))

main = do
  input <- map read . lines <$> readFile "input22"
  print . sum $ map ((!! 2000) . iterate next) input
  print . maximum $ Map.unionsWith (+) $ map bananaCounts input

Advent Of Code

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An unofficial home for the advent of code community on programming.dev! Other challenges are also welcome!

Advent of Code is an annual Advent calendar of small programming puzzles for a variety of skill sets and skill levels that can be solved in any programming language you like.

Everybody Codes is another collection of programming puzzles with seasonal events.

EC 2025

AoC 2025

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console.log('Hello World')

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