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+-- requires cabal install --lib megaparsec parser-combinators
+module Main (main) where
+
+import Control.Applicative.Permutations
+import Control.Monad (void, when)
+import Data.Char qualified as C
+import Data.Either
+import Data.Functor
+import Data.List qualified as L
+import Data.Map qualified as M
+import Data.Maybe
+import Data.Set qualified as S
+import Data.Void (Void)
+import Text.Megaparsec
+import Text.Megaparsec.Char
+
+import Debug.Trace
+
+exampleExpectedOutput = 5905
+
+data Card = J | Two | Three | Four | Five | Six | Seven | Eight | Nine | T | Q | K | A
+
+instance Eq Card where
+ J == _ = True
+ _ == J = True
+ a == b = show a == show b
+
+instance Ord Card where
+ a `compare` b = show a `compare` show b
+ a <= b = show a <= show b
+
+-- Dirty hack so that it sorts nicely in ascii
+instance Show Card where
+ show J = "0"
+ show Two = "2"
+ show Three = "3"
+ show Four = "4"
+ show Five = "5"
+ show Six = "6"
+ show Seven = "7"
+ show Eight = "8"
+ show Nine = "9"
+ show T = "A"
+ show Q = "B"
+ show K = "C"
+ show A = "D"
+
+data Rank = HighCard
+ | Pair
+ | Pairs
+ | Brelan
+ | FullHouse
+ | Quartet
+ | Quintet
+ deriving (Eq, Ord, Show)
+
+data Hand = Hand Rank [Card] Int deriving (Eq, Show)
+
+compareCards :: [Card] -> [Card] -> Ordering
+compareCards x y = concatMap show x `compare` concatMap show y
+
+instance Ord Hand where
+ (Hand a x _) `compare` (Hand b y _) | a == b = compareCards x y
+ | otherwise = a `compare` b
+
+type Input = [Hand]
+
+type Parser = Parsec Void String
+
+parseCard :: Parser Card
+parseCard = char '2' $> Two
+ <|> char '3' $> Three
+ <|> char '4' $> Four
+ <|> char '5' $> Five
+ <|> char '6' $> Six
+ <|> char '7' $> Seven
+ <|> char '8' $> Eight
+ <|> char '9' $> Nine
+ <|> char 'T' $> T
+ <|> char 'J' $> J
+ <|> char 'Q' $> Q
+ <|> char 'K' $> K
+ <|> char 'A' $> A
+
+evalRank :: [Card] -> Rank
+evalRank [J, J, J, J, _] = Quintet
+evalRank [J, J, J, d, e] | d==e = Quintet
+ | otherwise = Quartet
+evalRank [J, J, c, d, e] | c==d && d==e = Quintet
+ | c==d || d==e = Quartet
+ | otherwise = Brelan
+evalRank [J, b, c, d, e] | b==c && c==d && d==e = Quintet
+ | (b==c || d==e) && c==d = Quartet
+ | b==c && d==e = FullHouse
+ | b==c || c==d || d==e = Brelan
+ | otherwise = Pair
+evalRank [a, b, c, d, e] | a==b && a==c && a==d && a==e = Quintet
+ | (a==b && a==c && a==d) || (b==c && b==d && b==e) = Quartet
+ | a==b && (b==c || c==d) && d==e = FullHouse
+ | (a==b && b==c) || (b==c && c==d) || (c==d && d==e) = Brelan
+ | (a==b && (c==d || d==e)) || (b==c && d==e) = Pairs
+ | a==b || b==c || c==d || d==e = Pair
+ | otherwise = HighCard
+
+parseHand :: Parser Hand
+parseHand = do
+ cards <- some parseCard <* char ' '
+ bid <- read <$> (some digitChar <* eol)
+ return $ Hand (evalRank $ L.sort cards) cards bid
+
+parseInput' :: Parser Input
+parseInput' = some parseHand <* eof
+
+parseInput :: String -> IO Input
+parseInput filename = do
+ input <- readFile filename
+ case runParser parseInput' filename input of
+ Left bundle -> error $ errorBundlePretty bundle
+ Right input' -> return input'
+
+compute :: Input -> Int
+compute = sum . zipWith (*) [1..] . map (\(Hand _ _ bid) -> bid) . L.sort
+
+main :: IO ()
+main = do
+ example <- parseInput "example"
+ let exampleOutput = compute example
+ when (exampleOutput /= exampleExpectedOutput) (error $ "example failed: got " ++ show exampleOutput ++ " instead of " ++ show exampleExpectedOutput)
+ input <- parseInput "input"
+ print $ compute input