如何得到某集合的所有子集合?

王朝other·作者佚名  2006-01-09
窄屏简体版  字體: |||超大  

我们都知道,一个含n个元素的集合拥有2^n个子集合,并且不难发现,其中每个子集合都是从0到2^n-1 每个数的二进制格式中0 放弃,1选择的结果,如下所示:

{} 000

{1} 100

{2} 010

{1,2} 110

{3} 001

{1,3} 101

{2,3} 011

{1,2,3}111

所以根据数字的二进制转换,可以轻松获得一个集合的所有子集合,代码如下:

Sub GETALL(ByVal mycollection As String, ByRef RESULT() As String)

Dim x() As String

x = Split(Mid(mycollection, 2, Len(mycollection) - 2), ",")

Dim A() As String, b() As Integer '临时数组

Dim n As Integer ' 集合元素个数

Dim i As Long '循环变量

Dim num As Integer '子集合元素个数

Dim TEMP As Integer '二进制转换中间变量

n = UBound(x) + 1

ReDim b(0 To n - 1)

ReDim RESULT(2 ^ n - 1)

Debug.Print "集合 " & mycollection & " 共有子集合 " & 2 ^ n & " 个!"

For i = 0 To 2 ^ n - 1

TEMP = i

num = 0

For j = 0 To n - 1 '转换为二进制

b(j) = TEMP And 1 '0 or 1

TEMP = TEMP \ 2

If b(j) = 1 Then

num = num + 1

ReDim Preserve A(1 To num)

A(num) = x(j)

End If

Next

RESULT(i) = "{" & Join(A, ",") & "}" '结果保存

Debug.Print RESULT(i) '输出

Next

MsgBox "OK"

End Sub

Private Sub Command1_Click()

Dim S() As String

GETALL "{1,2,3,4,5,6}", S

End Sub

输出:

集合 {1,2,3,4,5,6} 共有子集合 64 个!

{}

{1}

{2}

{1,2}

{3}

{1,3}

{2,3}

{1,2,3}

{4}

{1,4}

{2,4}

{1,2,4}

{3,4}

{1,3,4}

{2,3,4}

{1,2,3,4}

{5}

{1,5}

{2,5}

{1,2,5}

{3,5}

{1,3,5}

{2,3,5}

{1,2,3,5}

{4,5}

{1,4,5}

{2,4,5}

{1,2,4,5}

{3,4,5}

{1,3,4,5}

{2,3,4,5}

{1,2,3,4,5}

{6}

{1,6}

{2,6}

{1,2,6}

{3,6}

{1,3,6}

{2,3,6}

{1,2,3,6}

{4,6}

{1,4,6}

{2,4,6}

{1,2,4,6}

{3,4,6}

{1,3,4,6}

{2,3,4,6}

{1,2,3,4,6}

{5,6}

{1,5,6}

{2,5,6}

{1,2,5,6}

{3,5,6}

{1,3,5,6}

{2,3,5,6}

{1,2,3,5,6}

{4,5,6}

{1,4,5,6}

{2,4,5,6}

{1,2,4,5,6}

{3,4,5,6}

{1,3,4,5,6}

{2,3,4,5,6}

{1,2,3,4,5,6}

 
 
 
免责声明:本文为网络用户发布,其观点仅代表作者个人观点,与本站无关,本站仅提供信息存储服务。文中陈述内容未经本站证实,其真实性、完整性、及时性本站不作任何保证或承诺,请读者仅作参考,并请自行核实相关内容。
 
 
© 2005- 王朝網路 版權所有 導航