Ask HN: How to prepare for technical interviews?

https://news.ycombinator.com/item?id=9170179

by thewarrior • 11 years ago

13 30 11 years ago

news.ycombinator.com

I'm good at my day to day job but I suck at whiteboard style interviews. I'd like to hear form any HN'ers who have gone from Level Zero to pro at acing tech interviews. How you prepared , what resources you used and how long it took.

smt882• 11 years ago

Whiteboard interviews are complete bullshit. I know that not everyone is lucky enough to work for companies that know that, but you should try.

Slightly more related to your question: once you get to a certain point, you shouldn't still be doing whiteboard interviews. Your resume and completed projects should tell the interviewers that you can code, or you should be moving to management (if that's your thing). I never even ask technical questions of someone who has good references from a few companies.

mrcold5• 11 years ago

Unfortunately it doesn't work like that. At multiple interviews I was asked to do code challenges or solve FizzBuzz exercises. I replied something along the lines of "I built a commercial product all by myself. Here is the website so you can play with it. Here are some code samples.".

And the answer I got always left me speechless: "Well, I don't really know what code you used or if you actually wrote it. So we're just going to fizzbuzz you to make sure you're good. We do this with everybody".

This didn't happen just once. It was actually the vast majority. The no-whiteboard approach seems to work only with early-stage startups. Once a company starts settling, say hello to mindless bureaucracy.

smt882• 11 years ago

I understand that avoiding whiteboard interviews isn't always possible. I'd just suggest OP (and anyone else) try and see if they can.

valdiorn4• 11 years ago

It's not mindless to make sure a candidate can actually produce some code. You'd be surprised how often people are hopelessly fucking incompetent at actual coding.

I'm used to getting these alpha dog; VP-of-whatever from big investment banks (I work in finance), with a laundry list of stuff they have done. Sure ok, good for you, now write up a skeleton class for a linked list in any language of your choice... what's that, you're stuck? You can't remember the keywords for defining a new class in the language you've labeled yourself as an EXPERT in? really?

mrcold5• 11 years ago

Practice. There is nothing else that can prepare you better. Assume that you will fail the first 5 interviews and use them to learn. After a while, you get the hang of it and learn how to fake it for the real thing.

And remember, you do your best when you don't care about the job. If you do care, your nervousness and desire to impress will be perceived as incompetence. And at that point, you're just sabotaging yourself.

simarpreet007• 11 years ago

Fully agree with your second point.

sevilo• 11 years ago

I hear the second point all the time and I can agree with it from my personal experience, but what would be a good way to "not care"? For me, when I know I'm interviewing with a company that I'm excited about, it seems a lot harder to actually "not care" about it than just saying it.

dropit_sphere• 11 years ago

The best way to not care is to actually not care---to have another interview lined up with a company you're just as excited about.

mathgeek• 11 years ago

I'm sure you've heard it before, but Cracking the Coding Interview is still a great resource. Do the problems on a whiteboard or on paper. The sections on soft skills and interview prep are also gold.

Additionally, site likes Top Coder and Hacker Rank are great for brushing up on your algorithms and problem solving.

loumf2• 11 years ago

Ask friends for mock interviews.

bengali3• 11 years ago

this. I think there was a show HN in the past few months that offered this service?

loumf2• 11 years ago

I'm pretty sure any random person that has contact info in HN would mock interview you for practice.

nailer• 11 years ago

Whiteboard tests are an excellent way to tests someone's ability to:

- write using their hands

- face one direction and talk in another

- talk while coding

- estimate insertion space

- write in horizontally straight lines

- avoid getting ink on their sleeves

The best places I've interviewed at game me a machine, a problem, and some quiet time to solve it.

However for others, I bring pencil and grid paper, and ask to sit beside people and solve the problem with them looking over my shoulder.

kls• 11 years ago

I could not have said it better, white-boarding is about as far away from a persons coding routine as it gets. Not to mention we all rely on REPL and the debugger from time to time to save us from simple mistakes, there is no iterative process on the whiteboard. Interviewers that insist on white-boarding should be viewed as companies that don't "get it" and you should focus your time elsewhere.

dagw2• 11 years ago

I've never had a white board interview where the interviewer cared about syntax or simple mistakes. I always 'code' in a mixture of pseudo code, math notation and diagrams depending on what makes sense and no one has ever complained.

khangsile• 11 years ago

Some advice from when I studied for these no more than two months ago: 1. Cracking the Code - get ahold of it and read through it. It 'll give you all the topics that you should study through and some tricks that are helpful in implementations. You'll still need to use other resources in order to know the topics in depth, like I don't think it goes too in depth into dynamic programming, but the book does have a large amount of questions and solutions. 2. oj.leetcode.com - This is just a website kind of like how interviewstreet was, and something around 180 problems that are interview style problems. You should be fine if you can do the almost all of the medium or easy level problems and maybe some of the hard ones. For these, I'd definitely get out a notebook and write out solutions and then throw type them up, to get a feel for how whiteboarding is going to be. 3. If you've got friends who are in the same position, actual mock interviews in person are an enormous help. I had a couple friends get together, and one of us would do one problem at a time while the rest evaluated them - basically acted like the interviewer.

With regards to timeline, I think I started preparing for my first phone interview a week early. The first couple of days were definitely slow, but with 3 days left, I studied for a couple hours each day before. For my first onsite, I found out about oj.leetcode.com about two weeks before and just did those problems almost non-stop for the two weeks leading up. Five days before the onsite, I rounded up some friends and we started doing whiteboard problems for a couple hours each day.

I guess preparation time varies by person. I did a little bit of competitive programming before this, so I would say I had a little bit of a head start. However, before this, I probably couldn't program a binary search off the top of my head, or approach dynamic programming problems, but now, I can probably handle a decent amount of algorithmimc interview problems. I can't say I'm pro, but I'm apparently good enough.

Klockan• 11 years ago

It is very important to understand that you can't expect that your mind will work properly during an interview. So if you can't do it in your sleep then it isn't good enough. There are only two ways to reach this stage, either it becomes second nature to you or you memorize everything. If you still want to proceed then you can try these steps:

Firstly you need to learn to code small 10-20 line programs in your head (everything including proper syntax etc, if you printed a copy of your mental image it would compile), without that you get crippled just from being unable to properly reason about your code.

Secondly you need to build up an intuition for data structures and algorithms so that you can easily come up with solutions on the fly. Very few do this, some even thinks that it is impossible and assumes that the questions only test memorization.

As an alternative to the second step you can memorize a ton of algorithms and continue going to interviews till you get a question you have memorized. This is what people usually do which isn't strange since this is how most pass their CS exams.

The first step is easy, just stop using your favorite IDE and use something simple like notepad. When you are comfortable with writing code in notepad then you are ready for interview programming.

The second step is harder and will take years. The easiest way to get better at this is to try to solve problems without help. You can start by reading up on different data structures/algorithms on wikipedia and then try to implement them in your favorite language. You can do competitive programming in parallel to practice speed and try out your implementations on tests which are much better at finding bugs than any interviewer.

The alternative second step can take any amount of time depending on how lucky you are. Minimum is to memorize FizzBuzz by writing it over and over in notepad till you get it right 20 times in a row. This can be done in a day even if you are an idiot. From there you can continue adding solutions to problems till you get the job you want. Then just forget everything and come back complaining once you want another job. This already happened once for fresh CS graduates since they forgot what they crammed for their tests so now they need to cram again and again for every interview.

dagw2• 11 years ago

The problem most people have with whiteboard interviews is that they have no strategy in mind before they start. They just step up to the whiteboard and hope inspiration will strike. My recommendation is to read Polya's How to Solve It. Then just follow the steps it presents once you get in front of the whiteboard. This way even if you don't immediately know how to solve the problem they present you at least have somewhere reasonable to start and a general map to follow.

MalcolmDiggs• 11 years ago

The best technical interview prep (IMHO) is to go on lots of warmup interviews. In other words, apply to lots of companies, and start with the interviews at places you might not actually want to work. Gradually build up to the high-pressure interview at your dream employer. Once you're in that room you'll be well practiced and ready for anything.

Ask HN: How to prepare for technical interviews?

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