Re: [Haskell-cafe] How to take a minimum sub list that only contain certain number of elements of certain type?

On 26 September 2012 03:56, Gwern Branwen wrote:

On Tue, Sep 25, 2012 at 1:42 PM, Rishabh Jain wrote:

...

f x 0 = [] f (x:xs) y | x `mod` 2 == 0 = x : (f xs y) | otherwise = x : (f xs (y-1))

...

f [0..] 4 [0,1,2,3,4,5,6,7]

Tsk, tsk. So ugly. How's this:

...

let f x = take x . filter odd

f 4 [0..] ~> [1, 3, 5, 7]

Notice that 0 is excluded, since 0 is *even*, not odd: http://en.wikipedia.org/wiki/Parity_of_zero If this is a serious problem, one can always just prepend zero:

...

0 : f 4 [1..] ~> [0, 1, 3, 5, 7]

Except that your solution is incorrect, as Magicloud wanted the smallest _prefix_ that contained four odd numbers...

-- gwern http://www.gwern.net

_______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

-- Ivan Lazar Miljenovic Ivan.Miljenovic@gmail.com http://IvanMiljenovic.wordpress.com