9 lines
214 B
Haskell
9 lines
214 B
Haskell
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collatz :: Integral a => a -> [a]
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collatz 1 = 1:[]
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collatz x
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| even x = x:collatz (quot x 2)
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| odd x = x:collatz (3*x + 1)
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main = do
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putStrLn . show $ maximum $ zip (map (length . collatz) [1..1000000]) [1..]
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