|No such thing as a small change|
Re^2: RFC: Cribbage::Handby Limbic~Region (Chancellor)
|on Mar 31, 2006 at 17:58 UTC||Need Help??|
When calculating points for sums of 15 you do not need to consider the suit of the card. You can also consider 10, Jack, Queen, and King as the same since they all have the value of 10. This means that there are only 1993 unique hands necessary to calculate any cribbage hand for 15s. I used a brute-force approach of summing all combinations of cards in group sizes of 2-5.
I then realized that if there was no card present that had a value of 10 (T/J/Q/K), I could also safely determine the points resulting from 2/3/4 of a kind. The reason the code works may not be obvious so I have included comments.
If you have more than 1 2 of a kind or 3/4 of a kind then you can't possibly have a flush. I added a flag if I knew it was safe not to check. You also can't possibly have right-jack if no card has a value of 10 - another flag.
I could also determine the value of any straights if no card had a value of 10. Since there are only 10 possible sequences of cards that can score points for a run, I avoided using loops. I am just going to explain the algorithm and hope that the code is clear as a result.
The hand, the flags, and the score are outputed in 8 bytes. 5 for the hand, 1 for the flags, and 2 for the score.
Calculate Total Score
The first step in calculating the total score is to convert the argument into the same format used to precalulate. We then lookup that hand and get back a 3 element array.
We know that we only have to check for 2/3/4 of a kind, straights, and right-jack if a card with the value of 10 is present. The method for determining 2/3/4 of a kind and straights has already been covered. To determine if we have right-jack:
Finally, we address potential flushes if necessary.
Cheers - L~R