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

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2023-12-07 19:10:06 -08:00
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"