feat: complete day 2

solutions/Days/Day02.hs

@@ -1,16 +1,75 @@
+{-# LANGUAGE OverloadedStrings #-}
+
 module Days.Day02 (day02) where
 
 import AOC (Solution (..))
-import qualified Data.Text as T
+import Data.Bifunctor qualified as B
+import Data.Text qualified as T
 
 day02 :: Solution
 day02 = Solution parseInput part1 part2
 
-parseInput :: T.Text -> a
-parseInput = error "parseInput not defined for day 02"
+data Shape = Rock | Paper | Scissors
+  deriving (Eq)
+
+data Outcome = Win | Lose | Draw
+  deriving (Eq)
+
+convertToShape :: T.Text -> Shape
+convertToShape x
+  | x == "A" || x == "X" = Rock
+  | x == "B" || x == "Y" = Paper
+  | x == "C" || x == "Z" = Scissors
+  | otherwise = error $ show x
+
+convertToOutcome :: T.Text -> Outcome
+convertToOutcome "X" = Lose
+convertToOutcome "Y" = Draw
+convertToOutcome "Z" = Win
+
+parseInput :: T.Text -> [(Shape, T.Text)]
+parseInput input = map someFunc . T.lines $ input -- ["A Y", "B X"] -> [(Rock, Paper), (Paper, Scissors)]
+  where
+    someFunc :: T.Text -> (Shape, T.Text)
+    someFunc line = (convertToShape first, second)
+      where
+        [first, second] = T.words $ line
+
+score :: Shape -> Int
+score Rock = 1
+score Paper = 2
+score Scissors = 3
+
+part1 :: [(Shape, T.Text)] -> Int
+part1 input = sum $ map (\(opp, player) -> outcomeScore (opp, player) + score player) input'
+  where
+    input' = map (B.second convertToShape) input
+
+outcomeScore :: (Shape, Shape) -> Int
+outcomeScore (opp, player)
+  | player == beats opp = 6
+  | player == loses opp = 0
+  | otherwise = 3
+
+beats :: Shape -> Shape
+beats Rock = Paper
+beats Paper = Scissors
+beats Scissors = Rock
 
-part1 :: a -> Int
-part1 = error "part1 not defined for day 02"
+loses :: Shape -> Shape
+loses Rock = Scissors
+loses Paper = Rock
+loses Scissors = Paper
 
-part2 :: a -> Int
-part2 = error "part2 not defined for day 02"
+part2 :: [(Shape, T.Text)] -> Int
+part2 input = sum $ map (\(opp, player) -> outcomeScore (opp, player) + score player) shapeList
+  where
+    outcomeList = map (B.second convertToOutcome) input -- [(Shape, Outcome)]
+    shapeList = map outcomeToShape outcomeList
+    outcomeToShape (shape, outcome) =
+      let outcome' =
+            case outcome of
+              Win -> beats shape
+              Lose -> loses shape
+              Draw -> shape
+       in (shape, outcome')