3 numbers on 9 (vb net)

[anselmej]

Hello

i have a ist of 9 numbers
i need them grouped by 3, but only one time : 123 but not 213, 321, 231,...

the list >> 1,2,3,4,5,6,7,8,9

I must get (in any collection) >>
123
124
125
126
129
...
234
245
...


thank you for helping

[Dross]

Erm... what exactly are you asking for? An algorithm to do this? How many groups you will have?

If you want the total number of groups where order doesn't matter (so {1,2,3} is the same as {2,1,3}) then:

There are 9*8*7 groups with different orders accounted for - ignoring order, each group appears 3*2*1 times. Thus the number of groups you'll end up having is

9*8*7/3*2*1 = 84 distinct groups.

An algorithm shouldn't be too hard to make up.

[anselmej]

i was there

Private Sub TroisDeNeuf()
Dim neufa As New StringCollection
Dim neufb As New StringCollection
Dim neufc As New StringCollection
For a As Integer = 1 To 9
neufa.Add(a.tostring)
Next
neufb = neufa
neufc = neufa
Dim sb As New StringBuilder
Dim i As Integer = 0

For a As Integer = 0 To 8
For b As Integer = 0 To 8
For c As Integer = 0 To 8
If a <> b AndAlso a <> c AndAlso b <> c Then
sb.AppendFormat("{0} {1} {2}<br />", neufa(a), neufa(b), neufa(c))
i += 1
End If
Next
Next
'here i must remove i=+1
Next
Me.AddLiteral(i.ToString & "<hr />")
Me.AddLiteral(sb.ToString)
End Sub

i must not get 113 or 445 , each number must be different, and of course if i have allready 234, i cannot have 243

the numbers are not 1to 9 of course but i have an array with 9 numbers
like 14,7,45,102,58,66,24,87,55

[anselmej]

it works :

Dim neufa As New StringCollection
For X As Integer = 1 To 9
neufa.Add(X.ToString)
Next
Dim a, b, c As Integer

Dim sb As New StringBuilder
Dim i As Integer = 0

For a = 0 to 6
For b = a + 1 to 7
For c = b + 1 to 8
sb.AppendFormat("{0} {1} {2} <br />", neufa(a), neufa(b), neufa(c))
Next
Next
Next

Me.AddLiteral(i.ToString & "<hr />")
Me.AddLiteral(sb.ToString)