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Implement day 15, in Haskell.

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Bert Peters
2017-12-16 23:38:17 +01:00
parent 56fb300d3b
commit 924c76c3b3
3 changed files with 27 additions and 2 deletions
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2017/day-15/.gitignore vendored Normal file
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solution
solution.hi
solution.o

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2017/day-15/solution.hs Normal file
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import Data.Bits
genA n = n : genA ((n * 16807) `rem` 2147483647)
genB n = n : genB ((n * 48271) `rem` 2147483647)
judge :: (Integer, Integer) -> Bool
judge (a, b) = (a .&. 0xffff) == (b .&. 0xffff)
divisible :: Integer -> Integer -> Bool
divisible b = (== 0) . (`rem` b)
genA' n = filter (divisible 4) $ genA n
genB' n = filter (divisible 8) $ genB n
main :: IO ()
main = do
let aStart = 618
let bStart = 814
print $ length $ filter judge $ take 40000000 $ drop 1 $ zip (genA aStart) (genB bStart)
print $ length $ filter judge $ take 5000000 $ zip (genA' aStart) (genB' bStart)