As Densam said, if you run the simulator, that is the best way to test you project. I was once was told, anyone can program a plc, but experience enables you to program a plc well.
By comparing to a solution is not alway the best way, every one has their own way of acheiving different results, some are robust, and some are flaky, but more often than not, they will work.
Saying this though, I am sure that bill's version will be the best and most efficient for the simulator exercise.
Those exercises are very good, I spent some time using logixpro, and it gives you a good understanding of the basic concepts. Was last on the elevator sim, got it working, but never really got to finish the stopping for an up request if the car was travelling up and vice versa, may get back to it some day, when i have finished programming real plcs.