advent-of-code-2024/src/Day3.hs
2024-12-03 22:11:22 +02:00

74 lines
1.7 KiB
Haskell

{-# LANGUAGE OverloadedStrings #-}
{-# OPTIONS_GHC -Wno-name-shadowing #-}
module Day3 where
-- import Debug.Trace
import Data.String
import Data.Scientific (coefficient)
import Data.Attoparsec.Text (Parser)
import Data.Either (fromRight)
import Data.Maybe (catMaybes)
import qualified Data.Attoparsec.Text as P
import qualified Data.Text.IO as T
type Program = [Inst]
data Inst = IMult Integer Integer | IDo | IDont
deriving Show
parseInput :: Parser Program
parseInput =
catMaybes <$>
P.many1' (P.choice [ Just <$> parseMult
, Just <$> parseDo
, Just <$> parseDont
, Nothing <$ P.anyChar])
<* P.endOfInput
parseDo :: Parser Inst
parseDo = IDo <$ "do()"
parseDont :: Parser Inst
parseDont = IDont <$ "don't()"
parseMult :: Parser Inst
parseMult = do
_ <- "mul("
n1 <- toInteger . coefficient <$> P.scientific
_ <- ","
n2 <- toInteger . coefficient <$> P.scientific
_ <- ")"
pure $ IMult n1 n2
solveA :: Program -> Integer
solveA = sum . fmap mult
mult :: Inst -> Integer
mult (IMult n1 n2) = n1 * n2
mult _ = 0
solveB :: Program -> Integer
solveB = sum . fmap mult . cleanup
where
cleanup (x@(IMult _ _):xs) = x:cleanup xs
cleanup (IDo:xs) = cleanup xs
cleanup (IDont:xs) = forget xs
cleanup [] = []
forget ((IMult _ _):xs) = forget xs
forget (IDo:xs) = cleanup xs
forget (IDont:xs) = forget xs
forget [] = []
input :: IsString s => s
input = "xmul(2,4)&mul[3,7]!^don't()_mul(5,5)+mul(32,64](mul(11,8)undo()?mul(8,5))"
main :: IO ()
main = do
input <- T.readFile "inputs/day3.input"
putStrLn "Part 1"
let xs = fromRight [] $ P.parseOnly parseInput input
print $ solveA xs
putStrLn "Part 2"
print $ solveB xs