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From: Joey Mukherjee on 15 Feb 2010 05:55
I have N number of sets of numbers and I want to get every possible
combination from these numbers.

For example:

std::vector <int> set1;
std::vector <int> set2;
std::vector <int> set3;

for (int i = 0; i < 2; ++i) set1.push_back (i);
for (int i = 0; i < 16; ++i) set2.push_back (i);
for (int i = 0; i < 9; ++i) set3.push_back (i);

I want {0,0,0}, {0,0,1},.. {0,0,8}.. {1,15,8}

The number of sets can be anything as well as the number of elements
in each set. Ideally, I'd like to restrict certain values as well.
I've been looking at next_permutation but I am at a loss for how to
make this work with multiple sets.

Can someone give me some help?

Thanks,
Joey

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From: Larry Evans on 15 Feb 2010 13:13
On Feb 15, 4:55 pm, Joey Mukherjee <joe...(a)gmail.com> wrote:
> I have N number of sets of numbers and I want to get every possible
> combination from these numbers.
>
> For example:
>
> std::vector <int> set1;
> std::vector <int> set2;
> std::vector <int> set3;
>
> for (int i = 0; i < 2; ++i) set1.push_back (i);
> for (int i = 0; i < 16; ++i) set2.push_back (i);
> for (int i = 0; i < 9; ++i) set3.push_back (i);
>
> I want {0,0,0}, {0,0,1},.. {0,0,8}.. {1,15,8}
>
> The number of sets can be anything as well as the number of elements
> in each set. Ideally, I'd like to restrict certain values as well.
> I've been looking at next_permutation but I am at a loss for how to
> make this work with multiple sets.
>
> Can someone give me some help?

This sounds like a cross-product of the sets.
There is a c++metaprogramming method for calculating
this at compile time:

http://article.gmane.org/gmane.comp.lib.boost.user/55821/match=combinations

I think you should be able to code a runtime version of this
compile time version without too much trouble.

HTH.

-regards,
Larry



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