23 lines
555 B
Haskell
23 lines
555 B
Haskell
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import Data.List.Split (splitOn)
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lineSafe' :: [Int] -> Bool
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lineSafe' [] = True
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lineSafe'
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l@(_:xs) = (all (> 0) diffs || all (< 0) diffs) && all validItem diffs
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where
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diffs = zipWith (-) xs l
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validItem x = x /= 0 && abs x <= 3
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allRemoved :: [a] -> [[a]]
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allRemoved [] = []
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allRemoved (x:xs) = xs:map (x:) (allRemoved xs)
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lineSafe :: [Int] -> Bool
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lineSafe = any lineSafe' . allRemoved
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main :: IO ()
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main = print . length . filter testLine . lines =<< readFile "data.txt"
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where
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testLine = lineSafe . map read . splitOn " "
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