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plaster/factorize.hs

Created December 19, 2015 15:43
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素直な素因数分解
Raw
factorize.hs
factorize :: Integer -> [ Integer ]
factorize n = factorize' n $ takeWhile (\x -> x * x <= n) [ 2 .. n ] where
factorize' n [] = case n of
1 -> []
_ -> [n]
factorize' n ds@(d:ds') = case n `mod` d of
0 -> d : factorize' (n `div` d) ds
_ -> factorize' n ds'
main = interact $ show . factorize . read
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