42 lines
1.3 KiB
Haskell
42 lines
1.3 KiB
Haskell
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module Main where
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import System.Environment (getArgs)
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import System.IO (Handle, hIsEOF, hGetLine, withFile, IOMode(ReadMode))
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import Text.Read (readMaybe)
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import Data.List (sort)
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import Data.Char (isDigit, isSpace)
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mapSnd :: (b -> c) -> (a, b) -> (a, c)
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mapSnd f (a, b) = (a, f b)
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parseLine :: String -> IO (Int, Int)
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parseLine line = let (l, (_, r)) = (mapSnd (span isSpace). span isDigit) line
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in
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case readMaybe l >>= \l' -> readMaybe r
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>>= \r' -> return (l', r') of
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Just a -> return a
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Nothing -> fail "Input file is incorrectly formatted"
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readLists :: Handle -> IO ([Int], [Int])
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readLists h = do
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shouldStop <- hIsEOF h
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if shouldStop
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then return ([], [])
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else do
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line <- hGetLine h
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(l, r) <- parseLine line
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(ls, rs) <- readLists h
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return (l:ls, r:rs)
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computeDistance :: [Int] -> [Int] -> Int
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computeDistance l r = sum (zipWith (curry (abs . uncurry (-))) l r)
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main :: IO ()
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main = do
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args <- getArgs
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(fp:_) <- return args
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(l, r) <- withFile fp ReadMode readLists
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putStrLn ("Solution (Part 1) : " ++ show (computeDistance (sort l) (sort r)))
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