advent-of-code/2023/7/Main.hs

import           Data.Bifunctor (second)
import           Data.List (group, sort, sortOn)
import qualified Data.HashMap.Strict as HMS

cardOrder :: HMS.HashMap Char Int
cardOrder = HMS.fromList . zip "AKQT98765432J" $ [0 ..]

getWorth :: String -> [Int]
getWorth cards = handType:map (cardOrder HMS.!) cards
  where
    noJs = filter (/= 'J') cards

    jCount = 5 - length noJs

    groupedCards = map length . group . sort $ noJs

    handType = case length groupedCards of
      0 -> 1
      1 -> 1
      2 -> if minimum groupedCards == 1
           then 2
           else 3
      3 -> if maximum groupedCards + jCount == 3
           then 4
           else 5
      4 -> 6
      5 -> 7

solve :: [String] -> Int
solve = sum
  . zipWith (*) [1 ..]
  . map snd
  . sortOn (map negate . getWorth . fst)
  . map parseLine
  where
    parseLine = second read . splitAt 5

main :: IO ()
main = print . solve . lines =<< readFile "data.txt"