From: Dylan <mejari@...>
Date: 2009-09-02T04:00:05+09:00
Subject: Re: Nice algorithm for 'spreading' indexes across an array?

On Sep 1, 11:12 am, Dylan <mej...@gmail.com> wrote:
> On Sep 1, 9:41 am, Max Williams <toastkid.willi...@gmail.com> wrote:
>
>
>
> > Little ruby algorithm puzzle...
>
> > I have a situation where i have an array of 12 items.  If someone
> > chooses to have n of them (where n can be between 3 and 12) then i want
> > to always include the first and last, and then 'spread' the others out
> > as evenly as possible between the rest.
>
> > So, lets say for the sake of argument that the array holds the numbers 1
> > to 12.
>
> > >> arr = (1..12).to_a
>
> > => [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]
>
> > I would get results back like this
>
> > arr.spread(3)
> > => [1,6,12] (or [1,7,12], either is fine)
>
> > arr.spread(4)
> > => [1, 5, 9, 12]  (or [1,4,8,12] or [1, 5, 8, 12])
>
> > It feels like there should be a simple solution for this but i can't
> > think of a nice way.  Anyone?
>
> > thanks
> > max
> > --
> > Posted viahttp://www.ruby-forum.com/.
>
> This should do what you're looking for. It's not always going to be
> 100% the most spread out possible, but it looks like you're ok with
> that :)
>
> http://pastie.org/601932
>
> -Dylan

Here's an updated version that wont hang if you have more than one of
any number :)

http://pastie.org/602026