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Google Interview Questions Deconstructed: The Knight’s Dialer

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Re: Google Interview Questions Deconstructed: The Knight’s Dialer

#71

Post by joshuamorton »

CydeWeys wrote: post #42
throwaways885 wrote: post #13

Earlier quoted context omitted.

> 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.

Google 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…

They 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.

Re: Google Interview Questions Deconstructed: The Knight’s Dialer

#72

Post by Raidion »

pc86 wrote: post #43
thdc wrote: post #28

Earlier quoted context omitted.

I 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 concret…

Now 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.

If I was in that situation, I hope the booze comes in first.

Re: Google Interview Questions Deconstructed: The Knight’s Dialer

#73

Post by username90 »

murgindrag wrote: post #31

So here's the thing. And I know I'll get knocked to r/iamverysmart for this. It timed myself. It took less than 10 minutes from reading the problem to coding up a working dynamic programming solution (no peaking at the rest of the article). A big chunk of that was (unsuccessfully) trying to come up with a closed-form solution. I didn't get the log(n) solution until I found it existed at the bottom, but once the autho…

Note that you need to pass at least 4 out of 5 interviews, each asking about 2 questions. But yeah, you don't have to be a genius to get into Google nowadays. What you need is the creativity to solve problems you haven't seen before (which is why Google bans questions once they get out), basic algorithms skills and the programming skills to implement it at a reasonable pace.

Re: Google Interview Questions Deconstructed: The Knight’s Dialer

#74

Post by xienze »

kevincox wrote: post #68
mcqueenjordan wrote: post #8

This is a fun problem, but it's a terrible interview question for trying to hire software engineers.

Why? Note that the point of the problem isn't if you can solve it. It is how you approach it. A problem like this gives you a lot of signal. * Can the person program at all. * Do they consider the performance of possible solutions. * Are they good at explaining their thought process. * Do they consider edge cases? * Do they write tests? I'm not saying that it should be the only interview, or it is the most important.…

> * Can the person program at all. * Do they consider the performance of possible solutions. * Are they good at explaining their thought process. * Do they consider edge cases? * Do they write tests?

All good things to look for. The problem is, day-to-day you don't have to do all of those things in 45 minutes while several people at the table watch you. Personally I'm a fan of a short programming exercise (perhaps even this problem) that you can take home and walk through with the team at a later time. I know those are detested by some, but I think they're fair (assuming the task is not something outrageous; something that can be knocked out in an evening perhaps) and give a much better idea of what an employee is capable of.

Re: Google Interview Questions Deconstructed: The Knight’s Dialer

#75

Post by xienze »

jeffbee wrote: post #52
xienze wrote: post #44

Earlier quoted context omitted.

> A person who has never seen chess will spend more of the interview just trying to figure out what is meant by the Knight's move. I mean he explicitly spells it out as part of the problem. I highly doubt in an interview they'll just plop down a term like "knight's move" and refuse to clarify what is meant by it, if necessary. It's not exactly the sort of thing that takes living a life of privilege to understand.

The difference is on the margin. If typical candidates who reach the optimal solution reach it in the last 5 minutes, and if it takes 5 minutes to discuss with a non-chess-playing candidate how a knight moves, then you have severely disadvantaged that candidate.

> and if it takes 5 minutes to discuss with a non-chess-playing candidate how a knight moves

If it takes 5 minutes to explain how a knight moves I think that person might not be Google material...

Re: Google Interview Questions Deconstructed: The Knight’s Dialer

#76

Post by username90 »

noarchy wrote: post #41
username90 wrote: post #20

Earlier quoted context omitted.

What is your point? Companies wants to hire smart people which is why they have these interviews. This applies no matter what level people are at. "I forgot" isn't valid defense. All the people in these threads who says things like "I knew this but forgot" are really cringy.

The point may be that many (if they're truly senior, not someone with 3-5 years in the industry) will not have used these theories in 10+ years. The real-world application is questionable.

And my point is that I'd rather hire someone who didn't forget these things. When you learn something well you don't forget, it is like riding a bike. If you learned how to ride a bike 10 yards and then stopped and never did it again then you would forget how to do it, saying "I passed the bike riding test when I was 10, I don't need to do it again" isn't a good defense.

I mean, why did you even go to college if you intended to just forget everything afterwards instead of learning the things properly for life? I'd rather not hire people who just do the work necessary to pass and get the degree and don't want to learn more.

Re: Google Interview Questions Deconstructed: The Knight’s Dialer

#77

Post by egsmi »

warmfuzzykitten wrote: post #3

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.

> 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.

Re: Google Interview Questions Deconstructed: The Knight’s Dialer

#78

Post by itronitron »

pc86 wrote: post #37
gcheong wrote: post #16

Earlier quoted context omitted.

How 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?

Why would managers get employees' scores on random interview questions? Why would that affect project assignments months or years later? Why would we assume folks at Google in charge of creating effective interview processes wouldn't be capable of the most basic statistical analysis, by making sure they had a large enough sample, enough performance reviews for each employee, etc?

Because it is common for managers to be very engaged in the hiring process.

Re: Google Interview Questions Deconstructed: The Knight’s Dialer

#79

Post by username90 »

Judgmentality wrote: post #38
username90 wrote: post #20

Earlier quoted context omitted.

What is your point? Companies wants to hire smart people which is why they have these interviews. This applies no matter what level people are at. "I forgot" isn't valid defense. All the people in these threads who says things like "I knew this but forgot" are really cringy.

/r/woosh

Do you think this is a good way to discuss things at HN?

Re: Google Interview Questions Deconstructed: The Knight’s Dialer

#80

Post by itronitron »

mym1990 wrote: post #30

Is it just me or is it somewhat pointless to be lamenting the fact that this may or may not be a terrible part of the hiring process? At the end of the day if you sit down for the interview and are given this question, you can either do your best to solve it or walk out of the interview and go to a company that you feel is 'more worth your time'. When you're playing by Google's rules, there's not much to be accomplis…

One of the problems I have with these types of questions where the interviewer is going to 'help guide' the candidate is that there is way too much opportunity for the interviewer to stall the candidate, either intentionally or not, based on their own bias toward the candidate.

At the most extreme, these questions are a test for whether the candidate had the same CS professors as the interviewer.

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