>In one room, there are three switches. They control three lightbulbs in an adjoining room, but you don't know which switch controls which lightbulb. All switches are initially in the "off" position. You can't see the other room from where the switches are.
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>Your task is to find out which switch controls which lightbulb. You can manipulate the switches all you want, and then go ONCE into the adjoining room to inspect the lightbulbs.

1. Turn on switch 1 (S1) and turn it off after a while
2. Turn on S2 and go into a room
3. The cold lightbulb is controlled by S3
4. The worm but off is controlled by S2