53 lines
1.3 KiB
Haskell
53 lines
1.3 KiB
Haskell
module Main where
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import qualified AoC as A (extract)
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import Data.Maybe (catMaybes)
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import Text.Parsec (anyChar, char, digit, many1, parse, string, try, (<|>))
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import Text.Parsec.String (Parser)
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type Pair = (Int, Int)
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data Instruction = Multiply Pair | Do | Dont deriving (Show, Eq)
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parseMul :: Parser Pair
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parseMul =
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string "mul("
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*> ( (,)
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<$> (read <$> many1 digit)
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<*> (char ',' *> (read <$> many1 digit) <* char ')')
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)
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parseIns :: Parser [Maybe Instruction]
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parseIns =
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many1
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( try (Just . Multiply <$> parseMul)
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<|> (try (string "do()") >> return (Just Do))
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<|> (try (string "don't()") >> return (Just Dont))
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<|> (anyChar >> return Nothing)
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)
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part1 :: [Instruction] -> Int
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part1 = sum . map (\case Multiply (a, b) -> a * b; _ -> 0)
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part2 :: [Instruction] -> Int
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part2 =
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fst
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. foldl
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( \(s, e) ins ->
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case ins of
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Multiply (a, b) | e -> (s + a * b, e)
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Do -> (s, True)
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Dont -> (s, False)
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_ -> (s, e)
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)
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(0, True) -- (sum, enabled)
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main :: IO ()
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main =
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do
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raw <- readFile "./inputs/day3.in"
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-- parse the input
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let instructions = catMaybes . A.extract $ parse parseIns "" raw
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putStr "Part 1: " >> print (part1 instructions)
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putStr "Part 2: " >> print (part2 instructions)
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