There is a room with a door (closed) and three light bulbs inside the room. Outside the room, there are three switches, connected to the bulbs. You may manipulate the switches as you wish, but once you open the door, you can’t change them. All bulbs are in working condition, and you can open the door only once. Identify each switch with respect to its bulb.

Solution: Let the bulbs be X, Y, and Z.

1. Turn on switch X for 5 to 10 minutes. Turn it off and turn on switch Y.
2. Open the door and touch the light bulb.
   • If the light is on, it is bulb Y.
   • If the bulb is hot, it is bulb X.
   • If the bulb is cold, it is bulb Z.

They asked for DSA and SQL.