从1-9中选择3个数字的所有组合,如何计算呢?

从1-9中选择3个数字的所有组合,怎么计算呢?急!
有从1到9共计9个数字,请问,如果三个一组,可以组合成多少个“三国联盟”?

备注:213组合和312组合,代表同一个组合,只要有三个数字在一起即可。

请问用vb如何实现,把所有组合都算出來?

------解决方案--------------------
稍改一下:
VB code

Option Explicit

Sub Carry(a() As Long, ByVal m As Long, ByVal n As Long)
    Dim Idx As Long
    Idx = n
    While a(Idx) = m
        Idx = Idx - 1
        m = m - 1
    Wend
    a(Idx) = a(Idx) + 1
    While Idx < n
        Idx = Idx + 1
        a(Idx) = a(Idx - 1) + 1
    Wend
End Sub

Sub PrintCom(a() As Long, n As Long)
    Dim i As Long
    ReDim tmp(n)
    For i = 1 To n
        tmp(i) = a(i)
    Next
    Debug.Print Trim(Join(tmp))
End Sub

Private Sub Command1_Click()
    
    Dim m As Long, n As Long
    Dim i As Long
    m = 9
    n = 3
    ReDim a(m) As Long
    For i = 1 To m
        a(i) = i
    Next
    a(0) = -1
    Do
        DoEvents
        Call PrintCom(a, n)
        Call Carry(a, m, n)
    Loop Until a(0) = 0
    
End Sub

------解决方案--------------------
问题描述的有点不清楚

到底 "3个一组" 是算整个 "三国联盟" 还是算三国联盟中的一国

你的问题如果意思是 1~9 9个数字中 任取3个数字 有多少种组合 那就是 c(9,3)=84种
我1楼就是按照这个意思来解答的