I'd rather work with the person who would approach that by taking 3 hours to plan, 3 hours to code, and 2 hours to bug fix, rather than the "Ready, Fire, Aim" person who took 1 hour to code, 4 hours to fix what he did, 8 more hours to find his design was totally wrong and re-do major portions of it, 8 more fixing the bugs in that version........
Unless you plan to filter out the people who just jumped into the code, in which the exercise is just a trick question.