day2

Signed-off-by: Amneesh Singh <natto@weirdnatto.in>

day2.hs

@@ -0,0 +1,57 @@
+import Lib (split)
+
+-- we do not use a simple 9 value case cuz yeah
+
+main :: IO ()
+main = do
+  input <- readFile "day2.in"
+  putStr "Q1: "
+  print $ q1 input
+  putStr "Q2: "
+  print $ q2 input
+
+data Choice = Rock | Paper | Scissors deriving (Enum, Eq)
+
+q1 :: String -> Int
+q1 =
+  sum
+    . map
+      ( \[x, _, y] ->
+          let i = val x 'A'
+              j = val y 'X'
+           in fromEnum j + 1 + case () of
+                _
+                  | i == j -> 3
+                  | winCond i == j -> 6
+                  | otherwise -> 0
+      )
+    . lines
+
+q2 :: String -> Int
+q2 =
+  sum
+    . map
+      ( \[x, _, y] ->
+          let i = val x 'A'
+              j = val y 'X'
+           in 1 + case fromEnum j of
+                0 -> 0 + fromEnum (loseCond i)
+                1 -> 3 + fromEnum i
+                2 -> 6 + fromEnum (winCond i)
+      )
+    . lines
+
+val :: Char -> Char -> Choice
+val a b = toEnum (fromEnum a - fromEnum b) :: Choice
+
+winCond :: Choice -> Choice
+winCond c = case c of
+  Rock -> Paper
+  Paper -> Scissors
+  Scissors -> Rock
+
+loseCond :: Choice -> Choice
+loseCond c = case c of
+  Paper -> Rock
+  Scissors -> Paper
+  Rock -> Scissors