Subj : Re: combo numbering
To   : comp.programming
From : bob
Date : Thu Oct 06 2005 03:28 pm

A 52bit number has 4.50359963 =D7 10^15 possibilities, which is way too
high.  I'm planning on storing an array of 133,784,560 32 bit numbers
in memory, which takes up about 600 mb.  This is on a machine that has
only 768 MB of RAM.


Ed Prochak wrote:
> bob@coolgroups.com wrote:
> > If you have 52 cards and you choose 7, there are 133,784,560
> > possibilities.
> >
> > So, let's say you have 7 playing cards. Is there an easy way to convert
> > these cards into a number between 0 and 133,784,559?
>
> consider a 52bit number.
> bit position 0 is ace of spades
> bit position 1 is duece of spades
> bit position 2 is 3 of spades ... etc.
>
> the 7card hand is a 52bit number with seven 1 bits.
>
> You could also use four 13bit numbers , one per suit.
> that's easily just 4 ints.
>=20
> HTH,
>   ed

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