[TreeInBuxton]

When I did my A-Level (UK exams taken at the end of 16-18) Computing exam, this is pretty much along the lines of what they did.

Program source was released a month before the exam, to allow students to familiarise themselves with it, and the exam then gave a series of questions/modifications the students had to make (I think ours was based on a pack of cards, so we had to implement a shuffle algo, and a take x from top of deck, etc).