There are three switches in front of you, one of which controls a
lightbulb in an isolated room. You can turn any of the switches
on or off, but you can't tamper with them. You can only enter the
isolated room once, but that's it, and you can't see what's happening
in the isolated room without entering.
So in other words, you do what you can turn the switches on and off,
and then you view the results. That's it.
How can you tell which switch controls the bulb?
Not only is there a possible answer, but this can also be solved
with up to six switches and up to six bulbs, where you figure out which
bulb is hooked up to which switch.