53 lines
2.0 KiB
Haskell
53 lines
2.0 KiB
Haskell
import Data.List.Split (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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import Data.Graph (graphFromEdges, scc)
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import Data.Sequence (Seq, index, fromList)
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type Length = Int
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type State = ([Int], Int, Int)
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type Edge = (Int, Int, [Int])
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(%) = mod
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(//) = div
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(!) = index
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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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sparseHash :: [Int] -> String
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sparseHash lengths =
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let (hashed, _, _) = iterate (hash lengths) ([0..255], 0, 0) !! 64
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in concat . map (printf "%08b" . foldr xor 0) . chunksOf 16 $ hashed
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getEdges :: Int -> (Seq Char, [Edge]) -> (Seq Char, [Edge])
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getEdges ind (str, edges) = if str ! ind == '0' then (str, edges) else
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let row = ind // 128
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col = ind % 128
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neighbours = [(row + 1, col ),
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(row - 1, col ),
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(row, col + 1),
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(row, col - 1)]
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validNeighbours = filter isOne . map toIndex . filter inBounds $ neighbours
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in (str, (ind, ind, validNeighbours) : edges)
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where
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inBounds (r, c) = r >= 0 && r <= 127 && c >= 0 && c <= 127
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toIndex (r, c) = r * 128 + c
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isOne i = (str ! i) == '1'
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main :: IO ()
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main = do
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let hashes = concat $ map (sparseHash . (++ [17, 31, 73, 47, 23]) . map ord . ("ffayrhll-" ++) . show) [0..127]
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used = length . filter (== '1') $ hashes
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(_, edges) = foldr getEdges (fromList hashes, []) [0..128 * 128 - 1]
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(graph, _, _) = graphFromEdges edges
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print $ used
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print $ length . scc $ graph |