50 lines
1.4 KiB
Haskell
50 lines
1.4 KiB
Haskell
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module Main where
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import System.Environment (getArgs)
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import Text.Parsec (parse, many1, char, sepBy, endBy)
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import Text.Parsec.Char (endOfLine)
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import Text.ParserCombinators.Parsec (GenParser)
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import Text.ParserCombinators.Parsec.Number (decimal)
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type Report = [Level]
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type Level = Int
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reports :: GenParser Char st [Report]
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reports = endBy report endOfLine
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report :: GenParser Char st Report
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report = sepBy level (many1 (char ' '))
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level :: GenParser Char st Level
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level = decimal
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pairUp :: [a] -> [(a, a)]
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pairUp (a:b:tl) = (a, b) : pairUp (b:tl)
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pairUp _ = []
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allIncOrDec :: Report -> Bool
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allIncOrDec (a:b:tl)
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| a /= b = all (uncurry (if a < b then (<) else (>))) $ pairUp $ b:tl
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| otherwise = False
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allIncOrDec _ = True
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notTooDifferent :: Report -> Bool
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notTooDifferent (a:b:tl) = let dif = abs (a - b)
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in (1 <= dif) && (dif <= 3) && notTooDifferent (b:tl)
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notTooDifferent _ = True
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part1 :: [Report] -> Int
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part1 = length . filter allIncOrDec . filter notTooDifferent
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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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content <- readFile fp
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case parse reports fp content of
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Left e -> putStrLn ("Input file is incorrectly formatted : " ++ show e)
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Right r -> do
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putStrLn ("Solution (Part 1) : " ++ show (part1 r))
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-- putStrLn ("Solution (Part 2) : " ++ show (part2 r))
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