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Ingy döt Net 2023-07-01 11:58:00 -04:00
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commit cb5bb5e222
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Task/Perfect-shuffle/Haskell/perfect-shuffle.hs Normal file
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shuffle :: [a] -> [a]
shuffle lst = let (a,b) = splitAt (length lst `div` 2) lst
in foldMap (\(x,y) -> [x,y]) $ zip a b
findCycle :: Eq a => (a -> a) -> a -> [a]
findCycle f x = takeWhile (/= x) $ iterate f (f x)
main = mapM_ report [ 8, 24, 52, 100, 1020, 1024, 10000 ]
where
report n = putStrLn ("deck of " ++ show n ++ " cards: "
++ show (countSuffles n) ++ " shuffles!")
countSuffles n = 1 + length (findCycle shuffle [1..n])