Get permutations of array numbers

Bikesh, Midhun,

First, thank you for feedback.

Well ... probably I wasn't explicit enough with my last post: I've already found a solution and exposed it in my message.

Regards

First of all: it smells like recursion of course!

Since you also wanted to know the principle, I did my best to explain it human language. I think recursion is very easy most of the times. You only have to grasp two steps:

1. The first step
2. All the other steps (all with the same logic)

In human language:

In short:
1. The permutation of 1 element is one element.
2. The permutation of a set of elements is a list each of the elements, concatenated with every permutation of the other elements.

Example:

If the set just has one element -->
return it.
perm(a) -> a

If the set has two characters: for each element in it: return the element, with the permutation of the rest of the elements added, like so:

perm(ab) ->

a + perm(b) -> ab

b + perm(a) -> ba

Further: for each character in the set: return a character, concatenated with a perumation of > the rest of the set

perm(abc) ->

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

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

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

perm(abc...z) -->

a + perm(...), b + perm(....)