I want to generate all variations with repetitions of a string in C++ and I'd highly prefer a non-recursive algorithm. I've come up with a recursive algorithm in the past but due to the complexity (r^n) I'd like to see an iterative approach.

I'm quite surprised that I wasn't able to find a solution to this problem anywhere on the web or on StackOverflow.

I've come up with a Python script that does what I want as well:

import itertools

variations = itertools.product('ab', repeat=4)
for variations in variations:
        variation_string = ""
        for letter in variations:
                variation_string += letter
        print variation_string

Output:

aaaa aaab aaba aabb abaa abab abba abbb baaa baab baba babb bbaa bbab bbba bbbb

Ideally I'd like a C++ program that can produce the exact output, taking the exact same parameters.

This is for learning purposes, it isn't homework. I wish my homework was like that.