Sample Question #260 (brainteaser)
[By popular demand, another brainteaser. This one was supposedly one of those old Microsoft favorites…]
There are three identical-looking light bulbs in a window-less room (with opaque walls, of course). Outside the room next to the closed door are three unlabeled switches, each controling one of the three lights. You’re told that nobody knows which switch controls which light, but you know that initially all the lights are turned off.
You can flip each of the three switches one and off just once, and after you’re done flipping the switches you can open the door and go into the room once. (That is, you cannot come back out and flip the switches again.) How can you tell which light switch controls which light bulb?