On 29 May 2012 18:15, Gary <listgj-phpgene...@yahoo.co.uk> wrote:
> Okay, let's assume I have three "things", A, B, and C. I need to produce
> an array with a list of all possible combinations of them, however many
> there might be in those combinations: e.g. A, B, C, D, AB, AC, AD, BC,
> ABC (not sure if I've missed any!). Normally I'm pretty good at working
> this stuff out, but to be honest I'm struggling with this one, at least
> to do it in any kind of elegant way. Does anyone have any ideas?
Sure, but what you are asking for is a permutation and not a combination.
Here's a good read on the subject:
Here's the deciding difference:
* If the order doesn't matter, then it's a combination.
* If the order does matter, then it's a permutation.
A combination of ABC is ABC.
However, the permutation of ABC is:
Oddly enough, a "combination lock" is a misnomer -- it should be a "permutation
lock" because the order of the "combination" does matter.
In any event, here's the code for as large a permutation as you may want:
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