From 70860aea14c023e09e950ec3fab0bee39758a5e3 Mon Sep 17 00:00:00 2001
From: Julien Dessaux
Date: Thu, 7 Dec 2023 14:48:54 +0100
Subject: 2023-07 in haskell

---
 2023/07-Camel_Cards/first.hs | 110 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 110 insertions(+)
 create mode 100644 2023/07-Camel_Cards/first.hs

(limited to '2023/07-Camel_Cards/first.hs')

diff --git a/2023/07-Camel_Cards/first.hs b/2023/07-Camel_Cards/first.hs
new file mode 100644
index 0000000..0afd4a7
--- /dev/null
+++ b/2023/07-Camel_Cards/first.hs
@@ -0,0 +1,110 @@
+-- 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 = 6440
+
+data Card = Two | Three | Four | Five | Six | Seven | Eight | Nine | T | J | Q | K | A deriving (Eq, Ord)
+
+instance Show Card where
+  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 = "T"
+  show J = "J"
+  show Q = "Q"
+  show K = "K"
+  show A = "A"
+
+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:xs) (y:ys) | x == y = compareCards xs ys
+                           | otherwise = x `compare` 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 n@(a:b:c:d:e:_) | not (a<=b && b<=c && c<=d && d<=e) = evalRank $ L.sort n
+                         | a==b && b==c && c==d && d==e = Quintet
+                         | (a==b && b==c && c==d) || (b==c && c==d && d==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 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
-- 
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