day2

day2/main.hs

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+import System.IO
+
+data Part = P1 | P2
+
+
+
+
+data Shape = Rock | Paper | Scissors deriving (Eq, Show)
+
+
+shape :: Char -> Shape
+shape 'A' = Rock
+shape 'B' = Paper
+shape 'C' = Scissors
+shape 'X' = Rock
+shape 'Y' = Paper
+shape 'Z' = Scissors
+
+
+opShp :: String -> Shape
+opShp = shape . head
+
+beats = [(Rock, Scissors),(Scissors, Paper),(Paper, Rock)]
+
+myShp2 :: Char -> Shape -> Shape
+myShp2 'X' o = snd $ head $ filter ((== o) . fst) beats
+myShp2 'Y' o = o
+myShp2 'Z' o = fst $ head $ filter ((== o) . snd) beats
+
+myShp :: Part -> String -> Shape
+myShp P1 g = shape $ last g
+myShp P2 g = myShp2 (last g) (opShp g)
+
+
+shapeScore :: Shape -> Int
+shapeScore Rock     = 1
+shapeScore Paper    = 2
+shapeScore Scissors = 3
+
+
+instance Ord Shape where
+    Rock `compare` Scissors = GT
+    Scissors `compare` Rock = LT
+    s1 `compare` s2 = (shapeScore s1) `compare` (shapeScore s2)
+
+
+
+
+winScore :: (Shape, Shape) -> Int
+winScore (me, op)
+    | me <  op = 0
+    | me == op = 3
+    | me >  op = 6
+
+
+
+
+gameScore :: Part -> String -> Int
+gameScore p s = shapeScore me + winScore (me, op)
+    where me = myShp p s
+          op = opShp s
+
+
+
+
+handler :: String -> String
+handler s = (show $ sum $ map (gameScore P1) $ lines s) ++ "\n" ++
+            (show $ sum $ map (gameScore P2) $ lines s) ++ "\n"
+
+main :: IO ()
+main = do
+    interact handler