[erlang-questions] Can I do the same with a fold easily

Éric Pailleau <>
Mon Oct 19 22:53:52 CEST 2015


Hi,
I agree but like Joe says: let it work,  then optimize if needed. 
My main remark was: Splitting odd and even does not need to check odd then even, but check it is odd Else it is even (or contrary).
Regards 

Le 19 oct. 2015 4:54 AM,  a écrit :
>
> "Éric Pailleau" <> 
>
> > A number cannot be both even and odd, so simply take odd numbers in a 
> > variable O from list L , even numbers will be L -- O. 
>
> Here we run into the question "what does BEST mean?" 
>
> Now Xs -- Ys cannot assume anything about the contents of Xs or Ys, 
> other than them both being well formed lists.  So while it *could* 
> be implemented in O(|Xs|+|Ys|+|Xs|lg|Ys|) time by building some kind 
> of balanced search tree from Ys, or even better by building some 
> kind of hashed set, the cost of building the supporting data structure 
> would likely be worse than the cost of traversing L twice or using 
> lists:partition/2. 
>
>
>


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