Puzzle | 3 Bulbs and 3 Switches

There is a closed room with three light bulbs inside.

• You have a closed room containing three light bulbs.
• Outside the room, there are three switches, each connected to exactly one bulb (but you don’t know the mapping).
• You can toggle the switches (on/off) in any way before entering the room.
• You may open the door and enter the room only once.
• Once inside, you cannot touch the switches again — you can only observe the bulbs.

How can you determine which switch controls which bulb in a single visit?

Check if you were right - full answer with solution below.

Solution:
Let the three switches be X, Y, and Z, and let them control three light bulbs inside the room.

• Turn on switch X and leave it on for 5 to 10 minutes.
• After that time, turn off switch X and turn on switch Y.
• Leave switch Z off the entire time.
• Now open the door and enter the room.

Inside the room, observe the following:

• The bulb that is on is connected to switch Y (since it was turned on most recently).
• Of the remaining two bulbs:
  1. The bulb that is off but warm is connected to switch X (it was on earlier and is still warm).
  2. The bulb that is off and cold is connected to switch Z (it was never turned on).