From: RichardOnRails <RichardDummyMailbox58407@...>
Date: 2008-09-05T15:44:14+09:00
Subject: Re: Need a 40 LOC (ignoring comments) to be shorter -- suggestions 	wanted

On Sep 5, 1:34 am, "Eric I." <rubytrain...@gmail.com> wrote:
> On Sep 4, 9:40 pm, RichardOnRails
>
>
>
> <RichardDummyMailbox58...@uscomputergurus.com> wrote:
> > Hi All,
>
> > My middle-school granddaughter posed the following challenge to me:
>
> > Within 10 minutes, Use the digits 3 to 7 in any order
> > to form a three-digit multiplicand and a two-digit multiplier
> > such that their product is minimal.
>
> > Out of curiosity as to whether my guess was right,
> > and with a view toward eliciting an interest in her
> > for Ruby programming,  I wrote the program posted athttp://www.pastie.org/266447
>
> > The program reveals that I was wrong, but it took me about 40 lines of
> > code,
> > ignoring comments.  That would probably overwhelm her.  I was hoping
> > that
> > the code could be condensed with Ruby-isms.  BTW, I left some put’s in
> > there
> > intended to give her a sense of the programs functionality.
>
> > Any ideas/suggestions?
>
> Here's one solution that requires the 'permutation' gem:
>
> ====
>
> require 'rubygems'
> require 'permutation'
>
> perm = Permutation.for((3..7).to_a)
>
> min_product = 10**5
> min_values = nil
>
> perm.map do |p|
>   a = p.project
>   v1 = a[0, 3].to_s.to_i
>   v2 = a[3, 2].to_s.to_i
>   product = v1 * v2
>   if product < min_product
>     min_product = product
>     min_values = [v1, v2]
>   end
> end
>
> puts "#{min_values.first} * #{min_values.last} = #{min_product}"
>
> ====
>
> Eric
>
> ====
>
> Are you interested in on-site Ruby or Ruby on Rails training
> that uses well-designed, real-world, hands-on exercises?http://LearnRuby.co

Thanks, Eric,

I should have thought of looking for that.  I certainly know I was
analyzing 5! permutations.

My granddaughter is much more likely to delve into that a little
ways.  I doesn't look so intimidating :-)

Best wishes,
Richard