I must be missing something. Isn't the obvious trick:
int r = random(<sum of weights>);
int i = 0;
while (r > weights[i]) {
r -= weights[i];
}
return i;
This way, you only have to generate one random number.
Peter Drake
http://www.lclark.edu/~drake/
On Jul 15, 2009, at 8:55 PM, Zach Wegner wrote:
On Wed, Jul 15, 2009 at 10:37 PM, David Fotland<fotl...@smart-games.com
> wrote:
So many complex ideas :) Why not just multiply the weight of each
pattern
by a random number and pick the biggest result?
David
That involves generating N random numbers and then doing N-1
comparisons. The n-ary tree has only 1 random number and log N
comparisons, but has to be
incrementally updated (log N adds).
Also, I don't think the distribution is the same. Imagine two moves a
and b, with weights 2 and 1. The probabilities should be a=2/3 b=1/3,
but if you select two random numbers in a finite range, there's only a
1/4 chance that the second number is more than twice the first, which
is needed for b to be selected. I could be wrong here though.
Zach
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