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Op doesn't have time for interviews (programming.dev)
submitted 10 months ago by to c/programmer_humor@programming.dev
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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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[–] 54 points 10 months ago (13 children)

The official answer to this riddle is turn switch 1 on for a minute or so, switch it off then switch 2 on. if the bulb is hot but dark, its 1, if it's lit it's 2 and if it's out and cold its 3.

the adult answer is why do I have only one chance to walk in the room?

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  • [–] 9 points 10 months ago

    this is the classic answer but it also fails pure logic because the question only implies one of them actually works, and even then, it's only one of them. the truth is any number of them could work, or a specific combination, or a number of combinations, or it might be none. the bulb itself to could be busted. my point is not to be an uncooperative asshole but that a logic puzzle that relies on real world properties should cover its bases.

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  • [–] 11 points 10 months ago (8 children)

    if the bulb is hot

    if hot they're using out of date lighting, who the fuck uses incandescent bulbs this far into the 21st century? they have failed their interview with me.

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  • [–] 4 points 10 months ago* (6 children)

    LED do not have a 100% efficiency, and do produce waste heat. A lot less than an incandescence one, sure, but enough for that answer to be valid.
    Well, maybe you'd better wait 10min instead of one, to make sure the led lightbulb heats enough, but still...

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  • [–] 7 points 10 months ago

    Well, maybe you’d better wait 10min instead of one, to make sure the led lightbulb heats enough, but still…

    I tested this with a 5W IKEA LED light-bulb, since I was just doom scrolling, anyway:

    • After 1 minute of being on, the bulb was still room temperature.
    • After 10 minutes of being on, the bulb was lukewarm.
    • After 10 minutes of being off, the bulb was room temperature, though the fitting maybe felt slightly warmer. That latter will probably depend on your installation, and how well it is able to disperse the heat.

    This means that the solution either breaks down entirely, or is unreliable, since you are not (reliably) able to tell the first two buttons apart

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  • [–] 1 point 10 months ago (4 children)

    note the premise specifies HOT.

    none of my LED bulbs get hot even after hours. they do warm up from 'cold' but HOT?

    ymmv.

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  • [–] 1 point 10 months ago (3 children)

    The "premise" is detecting that a now dark light was recently turned on by feeling for residual heat. "Hot" is a relative term.

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  • [–] 1 point 10 months ago* (2 children)

    actually not really - hot specifies HOT; if it were room temp, warm, warmer than another that sat unused - sure. but you're only flipping it on for a short time. HOT?

    it's pedantic, but parsing is important here because some HR shitwad decided these silly stupid games were a valid hiring method on filtering pedants apparently

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  • [–] 1 point 10 months ago (1 child)

    I'm drunk and belligerent to not give a shit about pointless pedentry, but to finally assert that...it doesn't fucking matter. Back when actual humans still liked Google, back before we forgot they technically changed their name to Alphabet, back when their motto was "do no harm," they started interviewing engineers with clever brain teaser puzzles. Because at the time, Google was out "Think Differentlying" Apple. Web 2.0 was all the rage, connecting shit together in ways we didn't know we shouldn't was in vogue, so it made sense for them to ask software engineers about the traveling salesman dilemma and shit like that. Because they were designing things like Google Maps, and they needed people who could solve "find a route from all addresses in the United States to all other addresses in the United States on consumer-grade hardware."

    But "Someone who needs an ordinary LAMP stack for their completely unoriginal eCommerce website" Inc. decided to start interviewing IT guys the same way because it made them look hip, and as a result Elon Musk spent a quarter term as Chief Superpower Fucker Upper.

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  • [–] 1 point 10 months ago*

    do no harm

    you must be from a parallel timeline friendo. in this reality, google promised 'don't be evil', then trashed that.

    I remember those days, lived through them.

    it doesn't change the crux; you turned it on briefly and supposed can identify which one it was because it got HOT. this would not occur with LED lighting; only incandescent would get warm enough fast enough to maaaaybe work in this setting.

    DO NO HARM is the oath medical professionals take, aka they hippocratic oath. https://en.wikipedia.org/wiki/Hippocratic_Oath

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  • [–] 4 points 10 months ago

    the adult answer is why do I have only one chance to walk in the room?

    The actual adult answer is questioning why the switch is in a different room and if it's because of safety, demand for safety protocol

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