Permutation of an array, with repetition, in Java

Question

There are some similar questions on the site that have been of some help, but I can\'t quite nail down this problem, so I hope this is not repetitive.

This is a home

Answer 1

I just had an idea. What if you added a hidden character (H for hidden) [A, B, C, H], then did all the fixed length permutations of it (you said you know how to do that). Then when you read it off, you stop at the hidden character, e.g. [B,A,H,C] would become (B,A).

Hmm, the downside is that you would have to track which ones you created though [B,H,A,C] is the same as [B,H,C,A]