From: Mike Wilson <wmwilson01@...>
Date: 2005-10-23T10:54:40+09:00
Subject: Re: combination sums of several arrays

On 10/22/05, swille <sillewille@gmail.com> wrote:
> On 10/22/05, David Vincelli <micologist@gmail.com> wrote:
> > I'm writing a little BlackJack program for fun and I'm at the point
> > where I have to decide which point value to assign to a hand. As you
> > know, an Ace may be worth 1 or 11 in this game - whatever is closer to
> > 21 without going over.
> >
> > Considering this, I know I have to come up with an algorithm that
> > first determines what the different point values may be (the extreme
> > case may be that a player got all four aces, now I'd have to determine
> > all combinations of the players cards).
> >
> > This demonstrates some of the code I wrote:
> >
> > pl = Player.new
> > pl.hand.each { |card|  p pl.card.value }
> >
> > might produce this output:
> > [1, 11]
> > [5]
> > [10]
> >
> > For the above example, so what I'm looking for is a method that will
> > calculate all possible point totals. For this example  I'd get the
> > results [16, 26]
> >
> > I'm thinking I might do this by first building a binary tree, creating
> > unique branches that would add up to the results when I applied some
> > recursive algorithm to it. But I'm curious to know how other people
> > might do this? (I'm especially curious to see if anyone has some
> > solution that does not require building a tree and recursing..).
> >
> > Thanks,
> >
> > --
> > David Vincelli
> >
> >
>
> Maybe I'm not understanding what exactly you want, but I think I'd
> dump the [1, 10] thing and just count it as [1].  Then maybe something
> like:
>
> sum = pl.hand.inject { |sum, n| sum + n }
> if pl.hand.include?(1)
>     if sum + 10 <= 21
>         sum += 10
>     end
> end
>
> Or did I miss something?
>

Oh, yes, I did.  Multiple Aces...