You are stuck inside an office building, and you want to know what the temperature is outside. How do you find out?
Solution: The way this puzzle is stated, with no specified constraints, tells the candidate that the interviewer is looking for as many potential solutions as possible. While the constraints are unstated, most candidates understand that it’s not in their interests to have as their only response, “Break a window and put your hand (or a thermometer) outside,” or “Watch the weather report on TV.” In any case, the interviewer will shoot down the offered solutions. Nevertheless, start simple to test the unstated con-straints of the problem. Whatever the candidate says, he or she should be prepared for an objection. Here’s a typical scenario:
CANDIDATE: Well you could use X to find the temperature.
INTERVIEWER: OK, let’s say there are no Xs lying around.
CANDIDATE: OK, perhaps you could try Y.
INTERVIEWER: Y is broken. What else?
Eventually, the candidate has to consider what “outside” means in this puzzle.
CANDIDATE: I’m going to define “outside” as outside the atmosphere of the earth, in deep space, where the temperature is absolute zero.
Let’s see the interviewer argue with that kind of vision! If the candidate is sufficiently outside the box, the solution becomes clear.