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
>
>

Actually, wouldn't you need to evaluate at each hand?  So, you'd start
with 2 cards, at which point Aces are always 11.  After that it's
something like:

if pl.card.value == 1
    if sum + 11 <= 21
        pl.card.value = 11
    end
end

sum += pl.card.value