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