I got pretty much the same answer except I redefined the question, without the box and I stated that diamond is equivalent to ~box~ and I left the end of the answer as is simply because all statements were done b4 the answer was attempted.
Yes, that sounds good. Give the def for diamond before doing anything, and then work purely in terms of box. No real need to give the answer in terms of diamond at the end, then... but if diamond is what's specified, it's probably safer and "more complete" to do so? It's no extra work, really.