Gyro is right, but the question, I think...is wrong...
The one I heard, is there is one room, no windows etc, one door (solid), 3 ligt switched outside....same scenario, you can turn the switches on and off as you please.
Switch on two, wait a minute or two, switch one off, enter room...if light is on, its teh switch you left on, i flight is off and the bulb is warm, its the switch you turned on and off, if light is off and cold, its the 3rd switch.
With 3 rooms it i impossible to tell which switch operated which light, within that scenario.