How to get hired (or, 'The silly story of interviewing in the valley') • Hacker News Board

Re: How to get hired (or, 'The silly story of interviewing in the valley')

#21

Post by kenjackson » Mon, Dec 19, 2011, 7:22 PM UTC

rauljara wrote: post #17

I was flabbergasted that someone was asked implement a linked list in Ruby. My initial reaction was 'That is an incredibly stupid thing to do.' My slightly more in depth reaction was "Isn't that what mutable arrays are for?" And my final reaction was, "Maybe I'm missing something." At which point I tried to figure out the benefits of a linked list over a ruby array. I wasn't able to come up with a good reason to use…

Linked lists and arrays typically have different perf characteristics (although I don't know how Ruby arrays work).

For example if I give you an element of an array/linked list and tell you to insert a new element adjacent to it -- a linked list is a constant time insertion, whereas arrays are typically O(n).

Re: How to get hired (or, 'The silly story of interviewing in the valley')

#22

Post by sgrove » Mon, Dec 19, 2011, 7:23 PM UTC

observer1 wrote: post #16

"....this process, starting from ~50+ raw leads whittled down into ~40 initial phone interviews/coding challenges, which went to ~25 next stage interviews, eventually down to ~6 really good offers, all in about ~1.5 weeks." Does this timeframe seem a little dubious to anyone else? I count 65 technical interviews plus interviews with hiring managers, etc., followed by receiving offers. And all of this happening in abo…

Nope, it's true. I woke up early in the morning (easy to do sleeping on the kitchen floor in mountain view without a heater), went through craigslist every morning, had an email template I'd individualize for each posting, and send it out. I'd work through the code challenges as they came in, set phone interviews into the late night, in-person interviews in the city during lunch, etc.

It happened, I took it pretty seriously because of the impending cliff of being homeless.

Re: How to get hired (or, 'The silly story of interviewing in the valley')

#23

Post by tptacek » Mon, Dec 19, 2011, 7:28 PM UTC

rauljara wrote: post #17

I was flabbergasted that someone was asked implement a linked list in Ruby. My initial reaction was 'That is an incredibly stupid thing to do.' My slightly more in depth reaction was "Isn't that what mutable arrays are for?" And my final reaction was, "Maybe I'm missing something." At which point I tried to figure out the benefits of a linked list over a ruby array. I wasn't able to come up with a good reason to use…

Linked lists are overused even in C, where they have a natural expression.

The reason to use a list instead of an array is that it's cheap to insert/delete anywhere into a list, but expensive to do so in the middle of an array.

There's probably no expression of a list in Ruby where insertion is cheaper than inserting into an array. Perhaps if your "list" is a secondary Fixnum index on a larger pool of objects? At any rate, that's no longer a "linked list".

I think it's a silly question. I hope the expected answer is, "why would I ever do that?"

Re: How to get hired (or, 'The silly story of interviewing in the valley')

#24

Post by codenerdz » Mon, Dec 19, 2011, 7:29 PM UTC

I had a similar experience interviewing after being off the job market for a quiet a few years: You will be rusty initially, but then you will pick up steam.

Just like in your "real life", solving interview problems is not about reinventing the wheel with 100% custom solution, its about pattern recognition where the pattern is a problem you know a solution for. The more problems you solve(and possibly fail) the more data your internal pattern recognition algorithm(your brain) has to help you with the solution.

I dont see it as gaming the system, I see it as being able to prove that you are capable of problem solving.

Re: How to get hired (or, 'The silly story of interviewing in the valley')

#25

Post by abahgat » Mon, Dec 19, 2011, 7:37 PM UTC

Aqua_Geek wrote: post #2

Are these kinds of interview questions really that prevalent? From the hiring side of the table, I can understand wanting to quickly know whether somebody knows some of the "basics" like data structures and whatnot. But I can't help feeling that you're needlessly limiting your applicant pool to only those who got a CS degree (and paid attention during the process). Why is so much emphasis placed on the theory of how…

I guess that one of the advantages of such an approach is standardization, in particular if your company is big. Once you get a significant number of candidates, it may become more important to have some "objective" and quantitative way to rank your candidates by performance than to get a true understanding about how likely they are to get things done (how would you "measure" that?). At that point, it becomes more important to ensure uniformity of judgement across the pool of interviewers. Isn't that why they often ask programming puzzles: so that they can compare performance. If the price to pay for that is that some valuable candidate won't get an offer, they can live with that. At least, that's how I see it.

Of course the argument for startups will be different :)

Re: How to get hired (or, 'The silly story of interviewing in the valley')

#26

Post by tptacek » Mon, Dec 19, 2011, 7:48 PM UTC

kenjackson wrote: post #21

rauljara wrote: post #17

I was flabbergasted that someone was asked implement a linked list in Ruby. My initial reaction was 'That is an incredibly stupid thing to do.' My slightly more in depth reaction was "Isn't that what mutable arrays are for?" And my final reaction was, "Maybe I'm missing something." At which point I tried to figure out the benefits of a linked list over a ruby array. I wasn't able to come up with a good reason to use…

Linked lists and arrays typically have different perf characteristics (although I don't know how Ruby arrays work). For example if I give you an element of an array/linked list and tell you to insert a new element adjacent to it -- a linked list is a constant time insertion, whereas arrays are typically O(n).

That's a sensible point, but interpreter and runtime overhead crushes any cost savings you might get from adjusting links instead of the whole array backing store.

(Ruby arrays, at least in MRI, are basically STL vectors).

1000 inserts to the middle of a 1,000,000 element Ruby array happens so quickly you can barely perceive the delay. The same insert pattern to a basic Ruby linked list sets my machine on fire.

Re: How to get hired (or, 'The silly story of interviewing in the valley')

#27

Post by russell » Mon, Dec 19, 2011, 7:48 PM UTC

I use a similar approach. I spent 20 years as a consultant, so I did a lot of interviews. I would send out lots of emails. I didnt do many tailored emails, but I did a carefully tailored cover letter designed to be amusing to the HR ladies. You have to get by them first.

I figured the first few interviews were throw-aways, just to get my interviewing skills back up to speed and to find what this years interview questions were. Yes, they go in fads. One year the programming task of choice was to reverse the words in a string. See it a couple of times and you get too be pretty proficient.

I keep a stock of questions to push back. I havent issued programming challenges, but I have asked, "What is your pain point? What technical issue is causing you problems?" Usually we get into a long discussion of the challenges theyare facing.

Re: How to get hired (or, 'The silly story of interviewing in the valley')

#28

Post by prostoalex » Mon, Dec 19, 2011, 7:51 PM UTC

timr wrote: post #3

"Then, acting as though this was the first time I'd seen this problem, I would ask if it was ok if I thought aloud as I worked my way through the problem on the board. I'd mumble to myself about moving-this-piece-over-here and-now-we're-going-to-get-this, and lo-and-behold, I accidentally solved it in constant memory space, in C - a language I didn't even claim to be particularly good at! Only someone with amazing pr…

Unless the end result is a completely incompetent applicant getting an offer, I wouldn't call the system "horribly broken". Very few companies are in the business of reversing linked lists, and hence make binary decisions depending on the outcome of just that one question.

I don't think gaming the system is that trivial - an interview is a conversation, so things like computational complexity, runtime restrictions, data structures, implementation differences in various programming languages, and other things are bound to come into conversation. Now, if one can maintain that conversation as it moves along, and seem like a pleasant person to work with, it seems that they're no longer purely "faking".

Re: How to get hired (or, 'The silly story of interviewing in the valley')

#29

Post by angelbob » Mon, Dec 19, 2011, 7:55 PM UTC

observer1 wrote: post #16

"....this process, starting from ~50+ raw leads whittled down into ~40 initial phone interviews/coding challenges, which went to ~25 next stage interviews, eventually down to ~6 really good offers, all in about ~1.5 weeks." Does this timeframe seem a little dubious to anyone else? I count 65 technical interviews plus interviews with hiring managers, etc., followed by receiving offers. And all of this happening in abo…

The 25 next-stage interviews are the only part that sounds even slightly unrealistic to me. The phone interviews are 30-60 minutes each, so 40 of them is no problem (20-40 hours of work).

The next-stage interviews are going to vary from 1-2 hours to a full day, so I assume he didn't do many full-day interviews in that 10-11 days, or probably 7-8 workdays.

But startups are often far more willing to do remote interviews, interviews at weird times, interviews on weekends... It would be a packed 1.5 weeks, though.

Re: How to get hired (or, 'The silly story of interviewing in the valley')

#30

Post by tedunangst » Mon, Dec 19, 2011, 7:55 PM UTC

rauljara wrote: post #17

I was flabbergasted that someone was asked implement a linked list in Ruby. My initial reaction was 'That is an incredibly stupid thing to do.' My slightly more in depth reaction was "Isn't that what mutable arrays are for?" And my final reaction was, "Maybe I'm missing something." At which point I tried to figure out the benefits of a linked list over a ruby array. I wasn't able to come up with a good reason to use…

My first guess would be that a FIFO queue is more efficient as a list than an array, but maybe there's something weird about ruby that makes that untrue. I'd love to hear why.