Difference between revisions of "Talk:99 questions/Solutions/31"

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(And something as simple as this one...: new section)
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== And something as simple as this one... ==
 
== And something as simple as this one... ==
   
  +
<haskell>
 
isPrime :: Int -> Bool
 
isPrime :: Int -> Bool
 
isPrime n = all (\x -> n `mod`x /= 0) [2..sqr]
 
isPrime n = all (\x -> n `mod`x /= 0) [2..sqr]
 
where sqr = floor (sqrt (fromIntegral n :: Double))
 
where sqr = floor (sqrt (fromIntegral n :: Double))
 
  +
</haskell>
 
-- Assuming that a number is not a prime if he is divisible by any number between 2 and his sqrt
 
-- Assuming that a number is not a prime if he is divisible by any number between 2 and his sqrt

Revision as of 11:15, 14 October 2013

Does something as simple but as dump as this should be on the wiki ?

isPrime :: Int -> Bool
isPrime n | n <= 1 = False
isPrime n = isPrime' 2 n
    where isPrime' x n | x*x > n   = True
                       | otherwise = (n `rem` x) /= 0 && isPrime' (x+1) n

And something as simple as this one...

isPrime :: Int -> Bool
isPrime n = all (\x -> n `mod`x /= 0) [2..sqr]
	where sqr = floor (sqrt (fromIntegral n :: Double))

-- Assuming that a number is not a prime if he is divisible by any number between 2 and his sqrt