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Ask HN: Can engineers from Google or Facebook solve whiteboard questions easily?

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Re: Ask HN: Can engineers from Google or Facebook solve whiteboard questions easily?

#161

Post by Pissompons »

kamaal wrote: post #149
UncleMeat wrote: post #96

Earlier quoted context omitted.

Does your standard library have persistent functional thread safe radix trees? Because mine didn't so we had to write it.

Even if it didn't, that's really like an exception to most common use cases of those tools. Which is precisely why testing candidates on such questions doesn't make much sense. I understand every once in a while something like that needs to get written, but again that's like an exception.

As an employer though, what do you want to happen when your employee runs into an exception? Do you want them to flounder and have no idea how to solve it or do you want them to figure it out by doing some mildly novel design work?

Re: Ask HN: Can engineers from Google or Facebook solve whiteboard questions easily?

#162

Post by kamaal »

jarsin wrote: post #122
jfasi wrote: post #101

Earlier quoted context omitted.

I also work at Google and what mystifies me when I do interviews is just how consistently people manage to screw up even the medium difficulty questions. I used to love asking this question until it was banned: https://programmingpraxis.com/2012/01/20/knights-on-a-keypad... This is a great question because it has several levels of solutions: 1. A recursive solution that iterates over all sequences, exponential time a…

> t's shocking how few candidates actually got as far as solution How many people in the real world sit around and practice dynamic programming questions all day?? The answer is ZERO!

>>How many people in the real world sit around and practice dynamic programming questions all day??

You will surprised how many people as a matter of fact actually do this.

In fact for a lot of people the whole purpose of a day job is to pay them salaries so that practice interview questions to hop on the next jobs.

The bad news is many companies think these sort of puzzle solving skills are penultimate level of software engineering skills and pay top salaries, so these people don't even worry about being bad at their current jobs.

Do these for a few years, and pad big brands to your resume and then you are automatically considered something special and qualified for big title promotions.

Re: Ask HN: Can engineers from Google or Facebook solve whiteboard questions easily?

#163

Post by kamaal »

WorldMaker wrote: post #135
jfasi wrote: post #101

Earlier quoted context omitted.

I also work at Google and what mystifies me when I do interviews is just how consistently people manage to screw up even the medium difficulty questions. I used to love asking this question until it was banned: https://programmingpraxis.com/2012/01/20/knights-on-a-keypad... This is a great question because it has several levels of solutions: 1. A recursive solution that iterates over all sequences, exponential time a…

It becomes brutally difficult in the context of a time-limited interview. You have the pressures of: 1) anxiety about limited time, 2) anxiety about hidden "tricks" or "cleverness", 3) inter-personal anxiety. It's that last one that I think algorithms/white-board coding entirely fails to see the trees for the forest. You would think as an industry that seems to lean heavily towards introverts and people in various pl…

>>Then add in the ticking clock anxiety, that I don't feel like I have time to breathe, much less patiently tease out a solution to the problem.

The worst part about this is if you get the first attempt wrong. Then you have very little time to start again and go to a working solution.

By then your anxiety begins to multiply.

Re: Ask HN: Can engineers from Google or Facebook solve whiteboard questions easily?

#164

Post by jfasi »

sadamznintern wrote: post #156
jfasi wrote: post #153

Earlier quoted context omitted.

That wasn’t my intention, and I updated my comment to clarify. Did your interviewer offer suggestions or just sit there?

It may not have been the intention but I'm honestly aghast at the utter elitism coming out of Google and Facebook. I get that you are "superior humans" that are plucked from top institutions making 25% more than me at Amazon, but you don't have to keep emphasizing it. My interviewer offered suggestions. Finally I described memoizing it (can be done with 2 lines in Python with a dictionary) though he was more interest…

> I'm honestly aghast at the utter elitism coming out of Google and Facebook

I presume it's Google and Facebook's extremely high hiring bar that you're attributing to elitism? Let me attempt to reframe that for you in a way that I hope will let you let go of some of the anger I'm picking up on:

There's no denying that Google and Facebook target top-tier institutions and put their candidates through hell. However, I don't attribute this to elitism. I personally got my start at a less-than-stellar CS program, and I go out of my way to recruit there as an alum. I've detected no elitism from any recruiters, interviewers, or hiring managers, and I've seen a number of people hired as interns and full time engineers as a direct result of my outreach. If Google were as elitist an organization as you seem to think, I and the people I've helped get hired would never have had a chance.

So then what explains the high bar? Simple necessity. I can't share details, but the number of applications we receive for every opening is staggering. What's more, when we approach people in industry and academia, we see a high rate of interest. The blunt truth is that we are more selective about hiring because we can be. When a hundred people (not real figures) apply for each available posting and your hiring pipeline is staffed well enough to interview all of them, you'd better believe you're going to hire the best one in that pool. This isn't a Google thing, this isn't a Facebook thing, this is a rational actor thing.

So no, I don't think you're stupid for coming up with a suboptimal solution, I have no reason to think you're a bad engineer, and I wouldn't reject you because your background. However, given a pool of candidates of whom some got as far as solution 3 and some got as far as solution 1, I'm going to more enthusiastically recommend hiring the ones who got solution 3.

Re: Ask HN: Can engineers from Google or Facebook solve whiteboard questions easily?

#165

Post by vonmoltke »

jasondclinton wrote: post #86
thewarrior wrote: post #78

Earlier quoted context omitted.

What CAN you tell us about the internal data ? Why does the process persist if there's data showing its flawed ?

Cribbing from a famous quote: this interview methodology is the worst except for all of the others. We don't know what a systemic, better interviewing system would be.

I don't agree with your Winnie hijack unless you add "systematic" to that as well, like you did in the next sentence.

Perhaps the answer is that there is no systematic interviewing system that actually works well. It seems like trying to create one was the origin of all this pain, and the cargo-culting by companies that don't need a systematic process has amplified it.

Interviewing is an inherently social, inherently subjective process. Such things are highly resistant to systematic approaches.

Re: Ask HN: Can engineers from Google or Facebook solve whiteboard questions easily?

#166

Post by jfasi »

driverdan wrote: post #116
jfasi wrote: post #12

I often do, both for fun and to prepare myself to give a question I'd like to use in an interview. The thing about interview questions at Google is there's a very fine line they need to walk: if they're too easy they give no useful information about the candidate, and if they're too hard they can never be solved in 45 minutes, again yielding no useful information. You also need to be able to provide some hints, becau…

> if they're too hard they can never be solved in 45 minutes, again yielding no useful information I strongly disagree with the assertion that you get no useful information from an unsolved problem. The goal of giving a candidate a problem should not be to have them solve it. The goal should be to learn how they approach a problem, think it through, and work on solving it. Actually coming up with a solution is the le…

> As an interviewer I've intentionally given people problems that would take more time than they have

What are your experiences with this? I've thought about doing this but decided against it because I figure the candidate's anxiety and stress levels are already high enough without the knowledge that they've been given a problem that's impossible for them to solve.

Re: Ask HN: Can engineers from Google or Facebook solve whiteboard questions easily?

#167

Post by jarsin »

kamaal wrote: post #162
jarsin wrote: post #122

Earlier quoted context omitted.

> t's shocking how few candidates actually got as far as solution How many people in the real world sit around and practice dynamic programming questions all day?? The answer is ZERO!

>>How many people in the real world sit around and practice dynamic programming questions all day?? You will surprised how many people as a matter of fact actually do this. In fact for a lot of people the whole purpose of a day job is to pay them salaries so that practice interview questions to hop on the next jobs. The bad news is many companies think these sort of puzzle solving skills are penultimate level of soft…

Oh trust me I know. I was being a smart ass and pointing out that only people that don't live in reality do this stupid shit. Dynamic programming interview questions, in particular, are the epitome of the absurdity of technical interviews.

Re: Ask HN: Can engineers from Google or Facebook solve whiteboard questions easily?

#168

Post by sadamznintern »

jfasi wrote: post #164
sadamznintern wrote: post #156

Earlier quoted context omitted.

It may not have been the intention but I'm honestly aghast at the utter elitism coming out of Google and Facebook. I get that you are "superior humans" that are plucked from top institutions making 25% more than me at Amazon, but you don't have to keep emphasizing it. My interviewer offered suggestions. Finally I described memoizing it (can be done with 2 lines in Python with a dictionary) though he was more interest…

> I'm honestly aghast at the utter elitism coming out of Google and Facebook I presume it's Google and Facebook's extremely high hiring bar that you're attributing to elitism? Let me attempt to reframe that for you in a way that I hope will let you let go of some of the anger I'm picking up on: There's no denying that Google and Facebook target top-tier institutions and put their candidates through hell. However, I d…

>I presume it's Google and Facebook's extremely high hiring bar that you're attributing to elitism?

Yes and no. It's that I'm inferior and stupid for being at a lower tier company than at Facebook or Google. I can see it in every condescending hiring post about how easy it is to pass interviews without seeing similar problems before, switch companies and save for retirement and how nice it is to work at a company that treats you like an ubermensch.

>I've detected no elitism from any recruiters, interviewers, or hiring managers, and I've seen a number of people hired as interns and full time engineers as a direct result of my outreach.

I have absolutely heard of individuals from top tier schools getting easy questions while I got tougher ones, cases where people from top programs and other top companies (like Facebook) getting the benefit of a doubt in borderline situations, etc.

In some ways its even worse than at Facebook, at least at Facebook there isn't a hiring committee after a team match like there is at Google now.

Re: Ask HN: Can engineers from Google or Facebook solve whiteboard questions easily?

#169

Post by jstewartmobile »

jfasi wrote: post #101
habosa wrote: post #36

I work at Google and no it's not easy for us either. I've heard many of my coworkers joke that if they went through the interview process again they'd probably fail. That said I see two kinds of interviewers. One kind (the good kind) takes a medium difficulty question and uses it to explore the candidate's coding, algorithms, communication, and problem solving skills. The other kind has a super hard question with a s…

I also work at Google and what mystifies me when I do interviews is just how consistently people manage to screw up even the medium difficulty questions. I used to love asking this question until it was banned: https://programmingpraxis.com/2012/01/20/knights-on-a-keypad... This is a great question because it has several levels of solutions: 1. A recursive solution that iterates over all sequences, exponential time a…

English is a rich and fuzzy language. I have more trouble translating problems like this into human than I do solving them.

Sometimes interviewers will respond to questions about the question. Others will only repeat the question as-stated. With the latter, I'd be sunk.

Pólya's first principle.

Re: Ask HN: Can engineers from Google or Facebook solve whiteboard questions easily?

#170

Post by mlevental »

jfasi wrote: post #101
habosa wrote: post #36

I work at Google and no it's not easy for us either. I've heard many of my coworkers joke that if they went through the interview process again they'd probably fail. That said I see two kinds of interviewers. One kind (the good kind) takes a medium difficulty question and uses it to explore the candidate's coding, algorithms, communication, and problem solving skills. The other kind has a super hard question with a s…

I also work at Google and what mystifies me when I do interviews is just how consistently people manage to screw up even the medium difficulty questions. I used to love asking this question until it was banned: https://programmingpraxis.com/2012/01/20/knights-on-a-keypad... This is a great question because it has several levels of solutions: 1. A recursive solution that iterates over all sequences, exponential time a…

>A logarithmic time solution involving adjacency matrices, matrix multiplication, and binary decomposition of numbers.

can you post a link to this solution? sounds cool.

edit: lol i just realized this is simply multiplying the adjacency matrix and what you mean by binary decomposition of numbers is just exponentiation by squaring. it's funny now that i realized i'll probably never figure out the dp solution.

edit2: got it. number of length n paths for some key u is sum of n-1 paths across "knight neighbors" of u. base case is length 1 path which is just # of neighbors.

it's funny this problem is designed in a particular way. using the keypad instead of a chessboard lets you write down the graph by hand rather than actually procedurally generating it (which is awkward with lots of literal edge conditions to check).

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