Ask HN: Can engineers from Google or Facebook solve whiteboard questions easily? • Hacker News Board

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

#141

Post by sadamznintern » Tue, Aug 14, 2018, 4:52 PM UTC

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…

I was asked this question at a company (unicorn, but lower bar than Google, got the offer) and I only described #1. Thanks for calling me stupid though!

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

#142

Post by kamaal » Tue, Aug 14, 2018, 4:52 PM UTC

C4stor wrote: post #54

kamaal wrote: post #49

Earlier quoted context omitted.

Sorry, in almost all cases its really choosing over several ways of Joining the data, not writing SELECT *, not writing cross joins and learning SQL well. Which why I ask again. Please list your problem which is so novel it requires you to invent a novel algorithm. Please note statistics is a science that has existed for centuries now. Unless you are in a university, its highly unlikely you have a problem that will n…

I don't understand your point. It seems to me you mix statisticals approaches and algorithms, meaning you completely ignore the fact that code runs on computers, and that computers have mechanical characteristics, making two implementations of the same statistical approach wildly different in performance. I used to work at a company where some guys spent literally weeks inventing a fast way to do a dot product over h…

>>I used to work at a company where some guys spent literally weeks inventing a fast way to do a dot product over huge vectors.

Very nice that you bought up this point. This is exactly what I was trying to point out. If a team of full time working people took weeks to arrive at a working solution, despite a massive body of open knowledge available as a reference to prior solutions, there is absolutely no way a candidate can give even arrive at a decent direction to the solution in under 45 minutes in a interview situation.

No one is saying algorithms are not useful.

But there is a very big difference between knowing an algorithm and inventing an algorithm. Testing the former is no indication of the latter, as illustrated by your own example.

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

#143

Post by sadamznintern » Tue, Aug 14, 2018, 4:53 PM UTC

jasondclinton wrote: post #139

jfasi wrote: post #131

Earlier quoted context omitted.

What memorized algorithm does this test for? As far as I know there is no algorithm to do this, and this interview tests for algorithm design rather than memorization.

You said above that you have set LNH for a T3 writing out the obvious solution to your question. The problem is that optimizing that solution comes one of two ways: 1. having seen the specific class of problem before and knowing, as you're writing that solution, to stop and switch to the class of solution you've seen before that would solve the problem more efficiently, or 2. finishing the obvious, poorly performing…

I'm really glad someone is seeing this for what it is. Too often people claim that you should go for the naive solution first, and then iterate, when that really doesn't work in the dynamics of a normal interview.

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

#144

Post by sadamznintern » Tue, Aug 14, 2018, 4:53 PM UTC

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!

It is >0, and those people make more than me :(

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

#145

Post by sadamznintern » Tue, Aug 14, 2018, 4:57 PM UTC

mattm wrote: post #66

I came across a guy on Reddit a while back who was currently employed at Facebook. He thought he'd try making a video of him doing one of Facebook's interview questions thinking it'd be easy for him to do. He stumbled through the problem and didn't end up solving it in the timeframe that would have been allowed. It was good of him to still post it but it showed that someone currently employed at Facebook would have b…

I remember that video. I thought it was hilarious because the question was so easy anybody that has done leetcode would be able to identify it and code it in like 5 minutes. I've gotten it at 4 different companies!

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

#146

Post by sadamznintern » Tue, Aug 14, 2018, 4:58 PM UTC

smt88 wrote: post #117

sadamznintern wrote: post #76

Yes they absolutely can.

The other comments for this post seems to cast doubt on your assertion that they all can. Also, solving them in an interview is radically different from solving them for fun.

I know a lot of people at top companies. All of them have an innate ability to do these algorithm problems better than people like me - they can crank out solutions quickly and get offers almost everywhere they try.

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

#147

Post by [deleted] » Tue, Aug 14, 2018, 4:58 PM UTC

lynal wrote: post #32

Silhouette wrote: post #24

Earlier quoted context omitted.

Indeed, although it's not unheard of for mathematics lecturers at university to throw in a question within a twenty-question problem sheet for their course that is actually equivalent to some important unsolved problem, on the off chance that one of their students sees things in a totally new way and makes a ground-breaking discovery. Solving something NP-hard in linearithmic time would certainly qualify...

Do you have a cite/example of a lecturer doing that on an exam? Are there any examples where that has been successful? I had never heard of that happening! It would be extremely cool if it ever worked.

[deleted]

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

#148

Post by awareBrah » Tue, Aug 14, 2018, 4:59 PM UTC

newusertoday wrote: post #104

kjeetgill wrote: post #88

The question I recently got that I found annoying was this: Given input (4, 2, 3, -1, 5) and output (-30, -60, -40, 120, -24) what's the function between them? I don't actually mind doing whiteboard interviews even on minimal prep. I've gotten a few of the "flagship" company offers and failed a few. I think part of it is internalising that nothing is going to guarantee you anything. You can always hit a question you…

what is the answer y = -120/x ?

product of all elements except self. usually a follow up to this question is to dissalow the divide operator

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

#149

Post by kamaal » Tue, Aug 14, 2018, 4:59 PM UTC

UncleMeat wrote: post #96

kamaal wrote: post #28

Earlier quoted context omitted.

Those look like software design skills. Also the type of systems you describes use something like Hadoop, and use things like Hive and Pig on top of it. Once you get the data out you use Python or R. And you generally use a standard library to work with. That really SQL + general programming. What new problems are you working on that require you to invent novel algorithmic techniques?

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.

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

#150

Post by sadamznintern » Tue, Aug 14, 2018, 4:59 PM UTC

franzwong wrote: post #69

tinderliker wrote: post #42

I am a SWE at Google, and yes, most Googlers are pretty good at solving whiteboard problems. It's not like we are born with those solutions in our heads, but we enjoy solving those questions especially with other people. It's a lot of fun to "explore" answers to these questions, and that's what I think interviews are all about. I know HN hates whiteboard problems, but just like anything, you get good with it if you'r…

I also want to see how you guys solve these problems. People on youtube videos already know the answer. They just told you how to solve it. But I can't see how they approach to get the answer. I think that part is the most interesting and valuable part for non-talent like me.

>They just told you how to solve it. But I can't see how they approach to get the answer. I think that part is the most interesting and valuable part for non-talent like me.

I ran into this too when I was preparing for a loop, especially for more complicated DP and recursion problems.

I found a website called gorecursion [0] on Reddit and he is very good at describing these solutions from the naive case to the optimized case very well. This helped me quite a bit, but I still didn't get the offer.

[0]: http://www.gorecursion.com/