這題我不會 [數的集合]

Question

輸入一變數N，再輸入一個含有Ｎ個數的集合Ａ，然後輸出所有這個人Ａ集合的子集合。
範例輸入：
３
範例輸出：
｛ 1 ｝
｛ 2 ｝
｛ 3 ｝
｛ 1 , 2 ｝
｛ 1 , 3 ｝
｛ 2 , 3 ｝
｛ 1 , 2 , 3 ｝
｛ ｝ <--空集合

Answer 1

Private Sub Command1_Click()    Dim I As Integer, S As String, A() As String        Do      N = Abs(Int(Val(InputBox("請輸入正整數", , 3))))    Loop Until N        ReDim A(N - 1)    For I = 0 To N - 1        A(I) = I + 1    Next    Cls    Call Assembler(-1, S, A)End SubSub Assembler(ByVal D As Integer, ByRef S As String, ByRef A() As String)    Dim I As Integer        For I = D + 1 To UBound(A)        S = S & A(I) & ","        Print "{"; Left$(S, Len(S) - 1); "}"        Call Assembler(I, S, A)        S = Left$(S, InStrRev(S, ",", Len(S) - 1))    NextEnd Sub