5 ms·
Typical brain-teaser interview question that will have absolutely no correlation to on-the-job performance but makes the interviewer feel really smart. I though
by warmfuzzykitten 6y ago
Typical brain-teaser interview question that will have absolutely no correlation to on-the-job performance but makes the interviewer feel really smart. I thought Google had gotten away from these.
- joshuamorton 6y agoThis isn't a brainteaser. It's a programming problem. Brainteasers are like "how many ping pong balls fit in a 747" or "you wake up an inch tall in a blender, the blades start spinning in a minute. How do you survive."
- throwaways885 6y ago> how many ping pong balls fit in a 747 This one does seem useful. Being able to do back-of-the-napkin (i.e. fermi problem) calculations is a pretty good skill.
- watwut 6y agoBack of napkin that requires you to know what 747 is wrong be correlated with anything programming related.
- crocal 6y agoActually a typical GMAT question...
- toast0 6y agoIt might be an OK problem if the interviewee is familiar with 747s and ping pong balls, and will be interacting with physical objects as part of their job. I have a terrible time with physical measurments and area and space, but thankfully it's not relevant to my work.
- CydeWeys 6y agoGoogle does still use questions like this, it's just that they're relevant to programming/system design. So a question might be "How many servers are needed to run Gmail?" The reason the 747 question is bad is because it has little to do with programming and a lot to do with how much you happen to know about planes and ping pong balls and how to estimate volumes of irregularly shaped objects, none of which have much if any correlation with programming ability.
- joshuamorton 6y agoThey don't (for SWEs), or at least you aren't supposed to. I think for PMs there may be questions more in this realm, but for SWEs, your questions should all be programming problems.
- CydeWeys 6y agoA System Design interview is required for all senior+ SWE candidates, plus other roles like at least SRE: https://www.youtube.com/watch?v=Gg318hR5JY0 https://www.youtube.com/watch?v=Gg318hR5JY0 Similar but smaller questions along these lines are given to more junior candidates often enough too, as one of multiple questions.
- joshuamorton 6y agoYour right though that candidates can get system design interviews, but "how many servers does it take to run gmail" is not anything like a system design interview. "How would you architect gmail" is. System design questions by their nature don't really have a correct answer. Your right though that candidates can get system design interviews.
- CydeWeys 6y agoEstimating how much traffic needs to be handled and what kind of resources it would take to handle it are absolutely part of both of those questions, which in reality are the same interview problem because a System Design interview isn't a single question but rather a long series of guided questions that cover architecture, scaling, and a lot more.
- thdc 6y agoI agree that this isn't a brainteaser. The problem itself appears to be nonsensical with no real world value but as long as it is a well defined problem with a concrete solution then it should be fine. Ideally the interviewer should be looking for how you approach the problem and what you do to obtain an answer (whether they do or not is a separate topic) Granted, the 747 question also technically does have a concrete solution I guess, but I would end up asking things like what's the volume of a 747 and the dimensions of a ping pong ball and then point out there will be gaps as we fill the 747 with balls so it's not simply dividing the volumes, write a program based on these observations, give a disclaimer that it will most likely be inaccurate, and hope that is good enough to pass. But that blender question... uh yeah... I'd probably spend too much time asking clarifying questions to actually come up with something plausible.
- pc86 6y agoNow I'm just thinking about how I would survive in a giant blender. Whether or not someone is about to add ice seems like a pretty important variable.
- Raidion 6y agoIf I was in that situation, I hope the booze comes in first.
- username90 6y agoThe blender questions relies on knowing that muscle strength scales with the square and body mass scales with cube. This is why insects for example can be so strong relative to their weight. So if we scaled you down you would be strong enough to just jump out.
- zeroxfe 6y agoThis didn't seem like a brain-teaser to me. I thought it was a fun problem to try and solve.
- username90 6y agoThis isn't a brain teaser, they actually correlate with on-the-job performance. When I worked at Google I looked up their internal reports on the subject and they showed that the score people got on these algorithm interviews correlated pretty well with their performance ratings after they got hired. In other words the group of people who got hired even though they had low scores performed significantly worse than the people who got hired with excellent scores. Edit: This applies for senior engineers as well.
- happytoexplain 6y agoPersonally, I don't think correlation is good enough. I never doubted that people who are good with a single given abstract problem are correlated with people who are good candidates. So yes, it non-arbitrarily identifies good candidates, but it also arbitrarily eliminates a significant chunk of good candidates.
- username90 6y agoYeah, it eliminates a lot of good candidates. If you can't match Google on benefits then you should not copy their hiring strategy and get their rejects, instead try to get the diamonds their rough process misses by doing something different.
- vsareto 6y ago>but it also arbitrarily eliminates a significant chunk of good candidates. I think they know that and they're okay with it because they have the volume and cash. I think they routinely tell you to try again.
- pc86 6y agoEliminating good candidates is not in and of itself a bad thing if it a) decreases your risk of a bad hire, and b) you want to optimize to decrease the risk of a bad hire at the expense of eliminating some potentially great ones.
- gcheong 6y agoHow do they control for bias in that a person with a high or low score may just be perceived to do better or worse, may be given better or less opportunities, etc. if their scores are known to the managers, etc? In other words it’s a correlation but is is explanatory?
- 2OEH8eoCRo0 6y agoNot really. Simple recursive backtracking problem. They're more checking that you understand backtracking and recursion.
- egsmi 6y ago> will have absolutely no correlation to on-the-job performance How do you know? Maybe the interview was for a position on the AplhaZero team.