how to make possible combinations of numbers

[seco]

Hi
i have an array like this

groupid number
1 235
2 987
3 781
4 879
and so on .....

and i want to make a combination of groups that has sum between say 1000 and 1500 or what ever.

how to iterate through all possible combinations of all items (i mean if i have 10 groups it will be 10 power 10 combinations right?) so how to do that?

thanks in advance.

 

[Raven65]

Assuming order isnt important, and if you do it right, it wont be an exponential number of rows.

If we can say that Element1+Element2 is the same as Element2+Element1, you cut the iterations dramatically.

A quick rough pass at this yields:

Module Module1

    Sub Main()

        Dim myNumbers As New List(Of Integer)
        myNumbers.Add(255)
        myNumbers.Add(700)
        myNumbers.Add(685)
        myNumbers.Add(157)
        myNumbers.Add(238)



        For currentNumberIndex As Integer = 0 To myNumbers.Count - 1
            For currentPartnerIndex As Integer = currentNumberIndex + 1 To myNumbers.Count - 1
                If ((myNumbers(currentNumberIndex) + myNumbers(currentPartnerIndex) > 1000) And _
                    (myNumbers(currentNumberIndex) + myNumbers(currentPartnerIndex) < 1500)) Then

                    Console.WriteLine("Match found: " & myNumbers(currentNumberIndex) & " + " & myNumbers(currentPartnerIndex) & " = " & _
                        (myNumbers(currentNumberIndex) + myNumbers(currentPartnerIndex)))
                Else
                    Console.WriteLine("No Match: " & myNumbers(currentNumberIndex) & " + " & myNumbers(currentPartnerIndex) & " = " & _
                        (myNumbers(currentNumberIndex) + myNumbers(currentPartnerIndex)))
                End If
            Next
        Next
        Console.ReadKey()
    End Sub

End Module

Outputs:

No Match: 255 + 700 = 955
No Match: 255 + 685 = 940
No Match: 255 + 157 = 412
No Match: 255 + 238 = 493
Match found: 700 + 685 = 1385
No Match: 700 + 157 = 857
No Match: 700 + 238 = 938
No Match: 685 + 157 = 842
No Match: 685 + 238 = 923
No Match: 157 + 238 = 395

Which I am sure could be cleaned up, but I didn't look at it for to long...

 

[seco]

thanks for reply
you just make the combination between every 2 elements for adding and i have thousands of elements and i want to get all possible combinations. not just between every 2 elements but any number of the array with any number

if i have 4 elements it will be:
1+2
1+3
1+4
2+3
2+4
1+2+3
1+2+4
and so on....