使用vba选择长度为3的独特子集

Question

我正尝试从1到6的整数生成长度为3的独特子集。我玩过以下很多版本的脚本，但似乎总是碰到某种问题。如果有人能给我一些指示，那将是很棒的。谢谢。

Sub permuteTest() 

num = 6 
cRow = 1 

For i = 1 To num - 2 

    For j = 2 To num - 1 

     For k = 3 To num 

      Cells(cRow, 1).Value = i 
      Cells(cRow, 2).Value = j 
      Cells(cRow, 3).Value = k 

      cRow = cRow + 1 

     Next k 
    Next j 
Next i 

End Sub 

Answer 1

像这样：

Sub permuteTest() 

num = 6 
cRow = 1 

    For i = 1 To num - 2 
     For j = i + 1 To num - 1 
      For k = j + 1 To num 
       Cells(cRow, 1).Value = i 
       Cells(cRow, 2).Value = j 
       Cells(cRow, 3).Value = k 

       cRow = cRow + 1 
      Next k 
     Next j 
    Next i 

End Sub 

Answer 2

这个程序演示了如何解决。它生成字符串元组“3,4,1”，但是如果你喜欢，你可以修改为使用数组。不容易阅读，但如果你通过一切将明确。为了紧凑，我没有声明变量，所以运行WITHOUT Option Explicit。

Const T = 3 ' generate 3-tuples 
Const N = 6 ' using digits 1,...,6 

Private Sub Permute() 
    Dim cTuples As New Collection: Call cTuples.Add(Empty)  ' start w empty tuple (rank 0) 
    For i = 1 To T: Set cTuples = NewTuples(cTuples, N): Next i ' increase tuple rank T times using N digits 
    For Each vTuple In cTuples: Debug.Print vTuple: Next  ' display the results 
End Sub 

' helper func: turn a set of T-tuples into T+1 tuples 
Private Function NewTuples(Tuples As Collection, N As Integer) As Collection 
    Set NewTuples = New Collection 
    For Each vOldTuple In Tuples 
     For i = 1 To N: NewTuples.Add (AppendToTuple(vOldTuple, i)): Next 
    Next 
End Function 

' helper func: turn a single T tuple into a T+1 tuple 
Private Function AppendToTuple(Tuple, i) 
    If IsEmpty(Tuple) Then AppendToTuple = i Else AppendToTuple = Tuple & "," & i 
End Function 

得到的字符串的元组debug.print'ed到IMMED窗口（Ctrl-G）：

1,1,1 
1,1,2 
1,1,3 
1,1,4 
1,1,5 
1,1,6 
1,2,1 
1,2,2 
... 
6,6,5 
6,6,6