求助：如何从一个字符串中取得固定长度的所有字符串的组合

goodboyrwy 2003-12-22 02:24:03

例如，一个字符串"abcde",要求取出其中长度为2（也可以为3，4）的任意组合，则结果为aa,ab,ac,ad,ae,ba,bb,bc,bd,...,
如长度为3，则结果为aaa,abb,abc,abd...

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northwolves 2003-12-22

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Private Sub Command1_Click()
Dim temp
temp = Split(cnm("abcdefg", 5), ",")
For i = 0 To UBound(temp)
List1.AddItem temp(i)
Next
MsgBox List1.ListCount
End Sub

Function cnm(ByVal x As String, ByVal m As Integer) As String '递归代码
x = Trim(x)
Dim temp() As String, temp2() As String, temp3() As String, temp4() As String
Dim counts As Long, i As Long
ReDim temp(Len(x) - 1)
For i = 0 To Len(x) - 1
temp(i) = Mid(x, i + 1, 1)
Next
If m = 1 Then cnm = Join(temp, ",")
If m > 1 Then
temp2 = Split(cnm(x, m - 1), ",")
counts = UBound(temp2)
ReDim temp3(counts)
ReDim temp4(UBound(temp))
For j = 0 To UBound(temp)
For i = 0 To UBound(temp2)
temp3(i) = temp2(i) & temp(j)
Next
temp4(j) = Join(temp3, ",")
Next
cnm = Join(temp4, ",")
Erase temp
Erase temp2
Erase temp4
Erase temp3
End If
End Function

northwolves 2003-12-22

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以前写的递归代码：
Private Sub Command1_Click()

Dim temp
temp = Split(cnm("a,b,c,d,e,f,g", 4), "*")
For i = 0 To UBound(temp)
List1.AddItem temp(i)
Next
MsgBox List1.ListCount
End Sub

Function cnm(ByVal lottery As String, ByVal m As Integer) As String '递归代码
Dim temp, temp2
Dim all As String
Dim num As Integer, i As Long, j As Long
all = lottery
temp = Split(all, ",")
num = UBound(temp) + 1
If m = 1 Then cnm = Replace(all, ",", "*")
If m = 2 Then
For i = 0 To UBound(temp) - 1
For j = i + 1 To UBound(temp)
cnm = cnm & "*" & temp(i) & "," & temp(j)
Next
Next
cnm = Right(cnm, Len(cnm) - 1)
End If
If m > 2 And num >= m Then
all = Left(all, InStrRev(all, ",") - 1)

temp2 = Split(cnm(all, m - 1), "*")
For i = 0 To UBound(temp2)
If temp2(i) <> "" Then temp2(i) = temp2(i) & "," & temp(num - 1)
Next
cnm = Join(temp2, "*")
cnm = cnm & "*" & cnm(all, m)
If Left(cnm, 1) = "*" Then cnm = Right(cnm, Len(cnm) - 1)
If Right(cnm, 1) = "*" Then cnm = Left(cnm, Len(cnm) - 1)
End If
End Function