Combinatorics - How to combine elements of sets

[DimDim]

Lets say we have N set of M elements (not every set has the same number of elements).

The problem is that the number of sets (N) isn't known.

Those sets are created from the program and they could be hundreds of them. I don't know from the beginning how many are they. The number of set becomes known from the execution of the program.

How can we program to have all possible combinations between the elements, if we choose only one element from each set.

How can I make an interior loop to do that?

Can I do that in a database?

e.g.

{1,2}, {1,3,4}, {5,6}

1-1-5
1-1-6
1-3-5
1-3-6
1-4-5
1-4-6
2-1-5
2-1-6
2-3-5
2-3-6
2-4-5
2-4-6

 

[wyrd]

For an interior loop just make an ArrayList of ArrayLists, then something like..

foreach (ArrayList subList in mainList) {
   foreach (int value in subList) {
      Console.WriteLine(value);
   }
}

With SQL Server you could try toying with CROSS JOIN;
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/acdata/ac_8_qd_09_610z.asp

 

[JABE]

> Can I do that in a database?

Yup, you can. In SQL Server, use CROSS JOIN.

 

[Heiko]

100 Sets with 10 elements in each will give you
10 ^ 100 possible permutations.

You should consider restricting the number of possible sets, I think