Solve 2024-03

src/AoC/Y2024/D03.hs

@@ -1,6 +1,98 @@
-module AoC.Y2024.D03 (solve) where
+module AoC.Y2024.D03 (solve, example1, example2) where
+
+import Prelude hiding (many)
 
 import AoC.Riddle
 
+import Text.Regex.TDFA
+
+type Program = [Statement]
+data Statement
+  = Mul Int Int
+  | Disable
+  | Enable
+  deriving stock (Show)
+
+-- | example data
+--
+-- >>> part1 example
+-- 2
+-- >>> part2 example
+-- 4
+example1 :: Text
+example1 = "xmul(2,4)%&mul[3,7]!@^do_not_mul(5,5)+mul(32,64]then(mul(11,8)mul(8,5))"
+
+example2 :: Text
+example2 = "xmul(2,4)&mul[3,7]!^don't()_mul(5,5)+mul(32,64](mul(11,8)undo()?mul(8,5))"
+
+parseStatement :: String -> Maybe Statement
+parseStatement "do()" = Just Enable
+parseStatement "don't()" = Just Disable
+parseStatement ('m' : 'u' : 'l' : rest) =
+  let
+    xs = (rest =~ ("[0-9]{1,3}" :: String)) :: [[String]]
+   in
+    parseMul $ concat xs
+parseStatement _ = Nothing
+
+parseMul :: [String] -> Maybe Statement
+parseMul [a, b] = Mul <$> readMaybe a <*> readMaybe b
+parseMul _ = Nothing
+
+regex :: String
+regex = "(mul)\\(([0-9]{1,3}),([0-9]{1,3})\\)|(don\\'t)\\(\\)|(do)\\(\\)"
+
+regex2 :: String
+regex2 = "mul\\([0-9]{1,3},[0-9]{1,3}\\)|don't\\(\\)|do\\(\\)"
+
+parsePart1 :: Riddle -> Program
+parsePart1 riddle =
+  let
+    args = Prelude.concat (toString riddle =~ regex2 :: [[String]]) :: [String]
+    stmts = mapMaybe parseStatement args
+   in
+    stmts
+
+-- int :: Parser Int
+-- int = L.decimal
+
+-- pMul :: Parser Statement
+-- pMul = do
+--   _ <- string "mul"
+--   _ <- char '('
+--   a <- int
+--   _ <- char ','
+--   b <- int
+--   _ <- char ')'
+--   pure $ Mul a b
+
+-- pAny :: Parser ()
+-- pAny = void (many (satisfy (const True)))
+
+-- pPart1 :: Parser Program
+-- pPart1 = many (many pAny *> try pMul)
+
+evalPart1 :: Program -> Int
+evalPart1 = foldl' eval 0
+ where
+  eval :: Int -> Statement -> Int
+  eval r (Mul a b) = r + a * b
+  eval r _ = r
+
+evalPart2 :: Program -> Int
+evalPart2 = snd . foldl' eval (True, 0)
+ where
+  eval :: (Bool, Int) -> Statement -> (Bool, Int)
+  eval (True, r) (Mul a b) = (True, r + a * b)
+  eval (False, r) (Mul _ _) = (False, r)
+  eval (_, r) Enable = (True, r)
+  eval (_, r) Disable = (False, r)
+
+part1 :: Riddle -> Int
+part1 = evalPart1 . parsePart1
+
+part2 :: Riddle -> Int
+part2 = evalPart2 . parsePart1
+
 solve :: (MonadIO m) => Text -> m (Either Text Solution)
-solve _ = pure $ Left "not yet implemented"
+solve riddle = pure $ Right [fromIntegral $ part1 riddle, fromIntegral $ part2 riddle]