32 lines
766 B
Haskell
32 lines
766 B
Haskell
import Data.Char (isAsciiLower, isAsciiUpper)
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import Data.List (intersect)
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import Data.Text (Text)
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import qualified Data.Text as T (foldl, lines, splitAt)
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import Lib (readFile')
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main :: IO ()
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main = do
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input <- map parse . T.lines <$> readFile' "day3.in"
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putStr "Q1: "
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print $ q1 input
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putStr "Q2: "
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print $ q2 input
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q1 :: [[Int]] -> Int
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q1 = sum . map (\x -> head . uncurry intersect $ splitAt (div (length x) 2) x)
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q2 :: [[Int]] -> Int
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q2 [] = 0
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q2 input =
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let (cur, rest) = splitAt 3 input
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in (head . foldr1 intersect) cur + q2 rest
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parse :: Text -> [Int]
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parse = T.foldl (\xs x -> val x : xs) []
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val :: Char -> Int
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val c
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| isAsciiLower c = 1 + fromEnum c - fromEnum 'a'
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| isAsciiUpper c = 27 + fromEnum c - fromEnum 'A'
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| otherwise = 0
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