23 lines
583 B
Haskell
23 lines
583 B
Haskell
#!/usr/bin/env stack
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-- stack --resolver lts-12.5 script
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module Day5A where
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import Data.Bits (xor)
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import Data.Char
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import qualified Data.Foldable as F
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invertCase :: Char -> Char
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invertCase = chr . xor 0x20 . ord
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calcLength :: String -> String -> Int
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calcLength ys (x:y:xs)
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| x == invertCase y = if null ys
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then calcLength ys xs
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else calcLength (tail ys) (head ys:xs)
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| otherwise = calcLength (x:ys) (y:xs)
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calcLength ys [x] = calcLength (x:ys) []
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calcLength ys [] = length ys
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main :: IO ()
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main = interact $ show . calcLength "" . filter (/= '\n')
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