You're in a room with no windows, but 1 door. There's 1 light in the room but no switch. You can't see above or beneath the door. Outside of the room around the corner is 3 light switches.Only 1 of the light switches are connected to the light and the other 2 aren't connected to anything. When you go out of the room you have to shut the door and you can only leave the room and go back into the room once. How do you find out which light switch is the working one?