From: Robert Dober <robert.dober@...>
Date: 2007-05-01T16:26:10+09:00
Subject: Re: Array.which_long? ( I coded an extension for Array )

On 5/1/07, Robert Klemme <shortcutter@googlemail.com> wrote:
> On 01.05.2007 00:03, Robert Dober wrote:
> > On 4/30/07, Robert Klemme <shortcutter@googlemail.com> wrote:
> > <snip>
> >> >>
> >> >> def longest
> >> >>    lg = Hash.new {|h,k| h[k] = []}
> >> >>    each {|x| lg[x.size] << x}
> >> >>    lg.sort_by {|k,v| k}.last.pop
> >> >> end
> >> > good idea but I wanted inject :)
> >> >> <snip>
> >>
> >> That's an easy transformation (left as exercise for the reader, bonus
> >> points for a one liner). :-)
> >
> > inject( Hash.new{ |h,k| h[k]=[]} ){|h,e| h[e.size] << e}.sort_by....
>                                                        ^^^^
> The return from the block is missing. :-)
Yeah I did not like this so I did not test it, I forgot the return of
the block in the solution below too, but I liked the solution and
therefore tested it....
>
> > as this is not readable anymore let me golf a little bit
> >
> > inject([]){|a,e| a[e.size] = (a[e.size]||[])+[e];a}.last
> > hmm that is not too bad ;)
>
> Couldn't you just use ||= here?
>
> inject([]){|a,e|(a[e.size]||=[])<<e;a}.last
Indeed, I guess I was very tired!!!
Now the solutions complexity and length just seems right.
Thanks for getting this right.
>
> I like your idea to use the length as array index - that way no sorting
> is needed.  Brilliant!
Well that is grossly exaggerated, but thank you anyway, the idea was
yours of course I just used an Array instead of a Hash, that must be
my tiny Lua background.

Cheers
Robert

-- 
You see things; and you say Why?
But I dream things that never were; and I say Why not?
-- George Bernard Shaw