There are two rooms. One room contains ten switches, and the other contains ten lights. Each switch controls one light, and no two switches control the same light. It is not known which switch controls which light, and it is your job to label them.
The problem is that, when you flip a switch, you can not immediately see which light has been turned on/off. You have to walk into the other room in order to find out.
What is the least amount of trips needed to label the switches?
We will call a trip any time that you leave the room with the switches.
We will say that you are in the room with the switches, and that all of the lights are on.
Bonus thoughts: what patterns emerge as you increase the amount of switches/lights?