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