First and most importatly, try it.
If I understand your problem well enough ( which I'm not sure of, sorry), try to use hashes instead of arrays. If the imput number doesn't exist in the hash as a key you create it, if it does, you create another hash with the given key. Values are not important.
Tiresome. Maybe an expert has a better solution, but it would be useful to know, what will you use these arrays or hashes for.