Anagram Algortihm

[Troy Lundin]

Ok, I have scoured the internet for days and even checked these forums. I do have an idea of how the algorithm should work, I just have no idea how to implement it.

Say you have the word ABCDEF.

The way I figure to solve it is to split it into columns, per se.
|A|B|C|D|E|F|



So the first iteration would yield A, B, C, D, E, F. Now, using each of those in the first column, increment the second column.

AB
AC
AD
AE
AF

Increment the third column.

ABC
ABD
ABE
ABF

Since we have reached the last letter in the third column, back up and increment the previous column.

ACD
ACE
ACF

Notice I don't use ACB, as that is exactly the same as ABC in terms of being unique.
Since the last letter was used, increment the previous column again.

ADE
ADF <- Last letter reached, increment previous
AEF

That is all the UNIQUE three letter combinations possible. Now, step up to four letters

ABCD
ABCE
ABCF <- Last letter reached, increment previous
ABDE
ABDF <- Last letter reached, increment previous
ABEF

The third column cannot be F because that is the last letter and would only allow a three letter word, which we have done already. Back up another column.

ACDE
ACDF <- Last letter reached, increment previous
ACEF <- Last letter reached, increment previous
ADEF <- Last letter reached, increment previous

Again, the column cannot be D as it would end up a three letter word. That is all the four letter UNIQUE combinations.

ABCDE
ABCDF <- Last letter reached, increment previous
ABCEF <- Last letter reached, increment previous
ABDEF

That is all the five letter combinations. And then, of course, the only 6 letter combination, ABCDEF.

Now, here comes the fun part. Notice how all the above combination start with the first letter. To get a whole list starting with the second letter, hack off the first.

Example: ABCDE -> BCDE -> CDE -> DE -> D

Now that I have shown the method, I need help with the implementation.
Note that the word may have more than one of the same letter (e.g AABCDE) so I would need to keep track of the letter that I am on.

Say I just finished ABF and am heading to ACD. I need to know that I am changing the second column from the second letter to the third letter. That means that the third column cannot be any letter less than the fourth letter.

Thanks for helping.

[minitech]

I don't really understand that, but here's something for solving anagrams: (see comments at bottom)

Dim lettersgiven() As Char = {"a"c,"b"c,"d"c,"e"c,"f"c}
Dim results As New List(Of String)
For start As Integer = 0 To lettersgiven.Length - 1
     Dim usedindices As New List(Of Integer)
     For j As Integer = 1 To lettersgiven.Length
          Dim i As Integer = start
          While usedindices.Contains(i)
               i = (i + 1) Mod lettersgiven.Length
          End While
          usedindices.Add(i)
     Next
     Dim sb As New System.Text.StringBuilder()
     For Each i As Integer In usedindices
          sb.Append(lettersgiven(i))
     Next
     If LookupDictionary(sb.ToString()) Then results.Add(sb.ToString())
Next
'Now, results is a list of all the possible words.
'You'll need to provide a "LookupDictionary" method
'that returns True when it's a real word.

[Troy Lundin]

All that code did was take the first letter and stick it on the end.

So, with input of 'abcdef' I got:
bcdefa, cdefab, defabc, efabcd, fabcde

[stateofidleness]

are you trying to determine if a string is an anagram, or are you trying to generate your own anagrams?

[Troy Lundin]

I am trying to get all possible UNIQUE letter combinations of a specific string.
Retain and retina are not unique because they have the same letters.

I am thinking of using an integer array that will hold the current letter in a certain position.
If the input string is 'abcdef' then an array like so {2, 3, 4} would be 'cde'.
Basically, each index in the array is a column of the string (explained in the first post) and the value of that index is the actual letter.

In the example {2, 3, 4}; c is the first letter because the first index contains a 2. c is in index 2 of the input string.
I am still fiddling around. Thanks for the input thus far.

[VBDT]

I am trying to get all possible UNIQUE letter combinations of a specific string.

That is what you should have started in the first place.

Check my signature for Unique Combinations.