How do I delimit a string into all possible character groupings of size 1 to 4

Question

i would like to take any input string and delimit it into groups. each group may be at least one character and no more than 4 characters. How do I loop to create all possible combinations?

Example:

in-string: xoox

output: x|o|o|x, x|oo|x, x|oox, xo|o|x, xo|ox, xoo|x, xoox

I'm writing an asp .net app using VB, but I really just need the concept for the recursion. So, an example in any language that doesn't use a special method to accomplish this would help me.

Answer 1

Interestingly, your visual representation using | characters to represent combined positions in the array gives a clue to how to approach this problem.

You have 2^(n-1) possible combinations where n is the length of the text. You can represent all the possible split positions using a list of binary numbers of length n:

000
001
010
011
100
101
110
111

You should be able to loop through this list of binary integers and, treating 0s for a position as false and 1s for a position as true, determine which combinations should be joined together. After you finish this loop, you'll have all possible combinations of the text.

Granted, there's still a good bit of VB.NET work to be done in order to generate the list of binary numbers, create output lists, etc, but hopefully this can get you started.

Answer 2

Something like this...

Sub writeDelimination(ByVal toSplit As String, ByVal start As String)
    Dim top As Integer = 4
    If toSplit.Length < 4 Then
        top = toSplit.Length
    End If
    For i As Integer = 1 To top Step 1
        Dim split As String = toSplit.Substring(0, i)
        writeDelimination(toSplit.Substring(i, toSplit.Length - i), start + "|" + split)
    Next
    If top = 0 Then
        Console.WriteLine(start)
    End If
End Sub

You would do the first call to the sub as writeDelimination("xoox", Nothing)