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Op doesn't have time for interviews (lemmy.ml)
submitted 6 days ago by danhab99@programming.dev to c/programmerhumor@lemmy.ml
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Post:

You have three switches in one room and a single light bulb in another room. You are allowed to visit the room with the light bulb only once. How do you figure out which switch controls the bulb? Write your answer in the comments before looking at other answers.

Comment:

If this were an interview question, the correct response would be "Do you have any relevant questions for me? Because have a long list of things that more deserving of my precious time than to think about this!

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[-] mech@feddit.org 107 points 6 days ago* (last edited 6 days ago)
  • Use the heat of the bulb to determine if it was on. (Shows you can memorize stupid interview questions)
  • Ask a team member to coordinate with you in the other room. (You're a team player)
  • Use a cable locator (Proper tool for the trade)
  • Put your phone in the other room, stream camera feed to your work laptop (The tech approach)
  • Unscrew the bulb. Now you know that no switch controls the bulb (Exposing the flaw in the task's phrasing)
  • Open switch panel and disconnect one switch. Wait a day. If no one complains, disconnect the second. Wait a day. If no one complains, it's probably the third. For good measure, disconnect the third switch. If still no one complains, remove all switches and the lightbulb, since they're not needed anymore. (The Sysadmin approach)
[-] markstos@lemmy.world 20 points 6 days ago

I am the sysadmin and I approve this message.

[-] MrSmith@lemmy.world 20 points 6 days ago

I'm about to throw up.

[-] Eh_I@lemmy.world 7 points 5 days ago* (last edited 5 days ago)

Open switch panel and disconnect one switch. Wait a day. If no one complains, disconnect the second. Wait a day. If no one complains, it’s probably the third. For good measure, disconnect the third switch. If still no one complains, remove all switches and the lightbulb, since they’re not needed anymore. (The Sysadmin approach)

I used this method a few months ago in my breaker box. I needed to make room in it for an EV charger.

[-] varyingExpertise@feddit.org 2 points 4 days ago

So, how's the freezer doing by now?

[-] folaht@lemmy.ml 9 points 6 days ago* (last edited 6 days ago)

What about trying to figure out first what the other two buttons do? Maybe they turn on the light of the room you're in. And I can see light without entering a room right? Just open the door, no need to enter it. If not allowed, look at the foot of the door or try to see if the room has a window.

No need to buy fancy equipment or even go into the room at all.

[-] EvilHankVenture@lemmy.world 1 points 5 days ago

You're assuming they don't control something in the room with the light, or they could control the lights in your room and the light you're trying to check .

[-] Aeao@lemmy.world 2 points 6 days ago* (last edited 6 days ago)

I’ve seen Rick and Morty. I know what they do. Grab a shovel.

[-] chenyun_fan1905@lemmy.ml 6 points 6 days ago

I think if its LED then the heat of the bulb strategy won't work.

[-] varyingExpertise@feddit.org 3 points 5 days ago

Give it few minutes, they get warm as well.

[-] Tiger666@lemmy.ca 1 points 5 days ago

LED lights get hot. So hot their plastic frames melt slightly sometimes.

this post was submitted on 25 Dec 2025
248 points (97.3% liked)

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