How to print all permutations of String both iterative and Recursive way? VB.NET

Question

Can any one help me how to print all permutations of String both iterative and Recursive way? I prefer VB.NET or just pseudo code is fine.

Thanks in advance.

Answer 1

Recursive approach is as follows:

Base case: The permutation of 1 letter is one element.

General case: The permutation of a set of letters is a list each of the letters, concatenated with every permutation of the other letters.

Explanation:

If the set just have one letter then return that letter. permutation(a) -> a

If the set has two letters, for each letter return it and the permutation of the rest of the letters.

permutation(ab) ->

a + permutation(b) -> ab

b + permutation(a) -> ba

For each letter in set return the letter concatenated with perumation of the rest of the set of letters.

permutation(abc) ->

a + permutation(bc) --> abc, acb

b + permutation(ac) --> bac, bca

c + permutation(ab) --> cab, cba