51 lines
1.0 KiB
Haskell
51 lines
1.0 KiB
Haskell
import Data.Either (rights)
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import Data.List (intersect)
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import Data.Text qualified as T
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import Lib (readFile')
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import Text.Parsec
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parser :: (Stream s m Char) => ParsecT s u m ([Int], [Int])
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parser =
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do
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card <- string "Card" *> many1 space *> many1 digit <* char ':'
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many1 space
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winning <- many digit `sepBy` many1 space
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char '|'
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many1 space
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mine <- many digit `sepBy` many1 space
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return (read <$> init winning, read <$> mine)
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main :: IO ()
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main = do
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input <- T.lines <$> readFile' "day04.in"
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let parsed = rights . map (parse parser "") $ input
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putStr "Q1: "
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print
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. sum
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. map
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( (\x -> if x < 0 then 0 else 2 ^ x)
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. flip (-) 1
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. length
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. uncurry intersect
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)
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$ parsed
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putStr "Q2: "
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print
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. sum
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. consequence
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. map
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( \(x, y) ->
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length $
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intersect x y
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)
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$ parsed
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where
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consequence :: [Int] -> [Int]
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consequence [] = []
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consequence (x : xs) =
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let xs' = consequence xs
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in 1 + sum (take x xs') : xs'
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