23 lines
774 B
Haskell
23 lines
774 B
Haskell
{-# LANGUAGE BangPatterns #-}
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import Data.Function (on)
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import Data.Bits ((.&.))
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divisor = 2147483647
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factors = (16807, 48271)
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seed = (634, 301)
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count :: (Int, Int) -> (Int, Int) -> Int -> Int -> Int
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count pair masks acc times =
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if times == 0 then acc else
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let !next = nextMaskBy <$$> factors <**> masks <**> pair
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!eq = fromEnum . uncurry ((==) `on` (.&. 0xffff)) $ next
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in count next masks (acc + eq) (times - 1)
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where
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h <$$> (x, y) = (h x, h y)
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(f, g) <**> (x, y) = (f x, g y)
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nextMaskBy f d s = let t = (f * s) `mod` divisor in if (t .&. d) == 0 then t else nextMaskBy f d t
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main :: IO ()
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main = do
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print $ count seed (0, 0) 0 40000000
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print $ count seed (3, 7) 0 5000000 |