Hash is a great idea. Thanks! I'll implement the hash now. I build an array of arrays where each subset array has all the possibilities for that letter. So if

Hash is a great idea. Thanks! I'll implement the hash now. I build an array of arrays where each subset array has all the possibilities for that letter. So if the query was N then a[0] = [0,..,9]. Then I just pick a random element from each subset array and stitch them all together in order.