On Thu, Nov 1, 2012 at 4:12 PM, bob gailer <bgailer at gmail.com> wrote: > > Why not create theElements as a set to start with? > what is Set ADT? is it important that we know that? I suppose it's an implementation of the set abstract data type (i.e. operations such as add, union, difference): http://en.wikipedia.org/wiki/Set_%28abstract_data_type%29