用递归打出有N个元素的集合的全部子集

[lijunfeng]

用递归打出有N个元素的集合的全部子集
如：E={a,b,c}
打出：{},{a},{b},{c},{a,b},{b,c},{a,b,c}

要用递归做，大家帮个忙

[lijunfeng]

没人回答就算了。

[lijunfeng]

分数可不少呀。

[qiqunet]

Dim combo() As String

Private Sub Form_Click()
aa 6, "{a,b,c,d,e,f}" '总的执行函数(传入值)
End Sub

Sub aa(n As Integer, string1 As String)
ReDim combo(n - 1)
For i = 2 To Len(string1) '分解出各个元素
tempstr = Mid(string1, i, 1)
If tempstr = "}" Then Exit For
If tempstr <> "," Then
combo(j) = combo(j) & tempstr
Else
j = j + 1
End If
Next

For i = 1 To n - 1
Print combo(i) '打印单个元素
Next

bb n - 1 '调用递归函数
Print "ok"
End Sub

Function bb(n As Integer) As String '递归函数
If n < 0 Then Exit Function
bb = bb(n - 1) & combo(n)
Print bb
End Function

[qiqunet]

我用的是VB5, 如果是VB6的话用split()函数来分解单个元素就简单多了, 呵呵

[shenen]

up

[qiqunet]

Dim combo() As String, maxnum As Integer

Private Sub Form_Click()
aa 6, "{a,b,c,d,e,f}" '总的执行函数(传入值)
End Sub

Sub aa(n As Integer, string1 As String)
ReDim combo(n - 1)
For i = 2 To Len(string1) '分解出各个元素
tempstr = Mid(string1, i, 1)
If tempstr = "}" Then Exit For
If tempstr <> "," Then
combo(j) = combo(j) & tempstr
Else
j = j + 1
End If
Next
maxnum = n - 1

Do While maxnum >= 0
bb n - 1 '调用递归函数
maxnum = maxnum - 1
Loop

Print "ok"
End Sub

Function bb(n As Integer) As String '递归函数
If n < maxnum Then Exit Function
bb = bb(n - 1) & "," & combo(n)
Print "{" & Mid(bb, 2, Len(bb) - 1) & "}"
End Function

[shenen]

http://expert.csdn.net/Expert/topic/2332/2332312.xml?temp=.1893122