Post:
You have three switches in one room and a single light bulb in another room. You are allowed to visit the room with the light bulb only once. How do you figure out which switch controls the bulb? Write your answer in the comments before looking at other answers.
Comment:
If this were an interview question, the correct response would be "Do you have any relevant questions for me? Because have a long list of things that more deserving of my precious time than to think about this!
Even knowing the "correct answer" to this riddle for as along as I remember, I don't think it is right. For someone looking for how to handle this in an interview, I'd go with this:
I will fetch a friend or colleague to look at the bulb as I test the switches because:
It is by far the most obvious solution that literally everyone faced with this problem actually would use. It is easy to understand and will be easy to explain to others (if you, e.g. need to present or document what you did).
It is also a better solution: it is by far more robust against a large number of failure modes: e.g., if it turns out you are testing the wrong switch, the bulb is broken, more than one switch turn on the light, etc.
It scales better: the same solution trivially extends to N number of lightbulbs controlled by M number of switches; and at large N it will save time not having to reach each bulb.
It gives the opportunity to interact positively with a friend/coworker. Helping each other out with small necessary tasks builds team cohesion and work environment, and thus lowers the barrier for further collaboration, making us a more effective team in the longer run.