day2

2022/day02/day02.hs

@@ -0,0 +1,29 @@
+data Hand = Rock | Paper | Scissor deriving (Eq,Enum,Bounded,Show)
+instance Ord Hand where
+    compare x y = case fromEnum x - fromEnum y `mod` 3 of
+                    0 -> EQ
+                    1 -> GT
+                    (-2) -> GT
+                    _ -> LT
+
+(+.) :: Hand -> Int -> Hand
+(+.) a b = toEnum $ flip mod 3 $ (+) (fromEnum a) b
+
+
+main :: IO ()
+main = do
+  input <- map (concat . words) . lines <$> readFile "input"
+  print $ day2 id input
+  print $ day2 realStrat input
+
+toHands :: [Char] -> [Hand]
+toHands x = map toEnum $ (zipWith subtract [65,88]) (map fromEnum x)
+
+realStrat :: [Hand] -> [Hand]
+realStrat (a:b:[]) = [a,a +. fromEnum (b +. 2)]
+
+day2 :: ([Hand] -> [Hand]) -> [[Char]] -> Int
+day2 f = sum . map (play . f . toHands)
+
+play :: [Hand] -> Int
+play (x:y:[]) = fromEnum y + 1 + if x == y then 3 else fromEnum (x<y) * 6