30 lines
1.1 KiB
Haskell
30 lines
1.1 KiB
Haskell
import Data.List.Split (splitOn, chunksOf)
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import Data.Char (ord)
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import Data.Bits (xor)
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import Text.Printf (printf)
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type Length = Int
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type State = ([Int], Int, Int)
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(%) = mod
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twist :: State -> Length -> State
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twist (ring, position, skip) len =
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let rotated = slice position 256 $ cycle ring
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twisted = (reverse $ take len rotated) ++ drop len rotated
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newRing = slice (256 - position) 256 $ cycle twisted
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in (newRing, (position + len + skip) % 256, skip + 1)
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where slice start amount = take amount . drop start
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hash :: [Length] -> State -> State
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hash lengths state = foldl twist state lengths
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main :: IO ()
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main = do
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input <- readFile "10.txt"
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let lengths = map read $ splitOn "," input
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newLengths = map ord input ++ [17, 31, 73, 47, 23]
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(hashed, _, _) = hash lengths ([0..255], 0, 0)
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(sparseHash, _, _) = iterate (hash newLengths) ([0..255], 0, 0) !! 64
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hexString = concat . map (printf "%02x" . foldr xor 0) . chunksOf 16 $ sparseHash :: String
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print $ hashed !! 0 * hashed !! 1
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print $ hexString |