36 lines
954 B
Haskell
Executable file
36 lines
954 B
Haskell
Executable file
#!/usr/bin/env runghc
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import Data.Char
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data PasswordEntry = PasswordEntry { pos1 :: Int, pos2 :: Int, char :: Char, password :: String }
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deriving (Show)
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-- This could be a lot better...
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instance Read PasswordEntry where
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readsPrec _ input =
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let (pos1', rest) = span isDigit input
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pos1 = read pos1' :: Int
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(_, rest') = splitAt 1 rest
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(pos2', rest'') = span isDigit rest'
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pos2 = read pos2' :: Int
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(_:char:_:_:password) = rest''
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in
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[(PasswordEntry pos1 pos2 char password, "")]
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main = interact solve
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solve = show . length . filter (isValidPasswordEntry . readPasswordEntry) . lines
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readPasswordEntry :: String -> PasswordEntry
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readPasswordEntry = read
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xor :: Bool -> Bool -> Bool
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xor l r = l /= r
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isValidPasswordEntry (PasswordEntry pos1 pos2 char pass) =
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(charAtPos1 == char) `xor` (charAtPos2 == char)
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where
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charAtPos1 = pass !! (pos1 - 1)
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charAtPos2 = pass !! (pos2 - 1)
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