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Comment by danielvinson | Hacker News Reader

I’m a college dropout and have about 8 years of experience as a developer. I’ve been interviewing a lot lately at mostly startups (7 onsites in the last month). Every single place except for one asked me about college or why I dropped out. One place asked me incredibly difficult whiteboard problems which appeared to be to filter out people without CS degrees (very specific algorithms to implement which I’ve never heard of before). One place had me reverse a linked list on a whiteboard, and was rude and standoffish when I commented that I’d never thought about doing that before so I didn’t have the algorithm memorized.

The job I accepted is the one job that didn’t even mention my lack of a degree and gave me practical coding problems.

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> One place had me reverse a linked list on a whiteboard, and was rude and standoffish when I commented that I’d never thought about doing that before so I didn’t have the algorithm memorized.

A good interviewer prefers it if the candidate does not have the algorithm memorized. The whole point is to gauge their problem solving skills. Reciting something from a textbook doesn't tell the interviewer much. The reason you didn't get a favorable reaction in that situation could be because not knowing the algorithm was perfectly acceptable in that situation. It's expected that you figure it out instead of challenging the validity of the question.

In this case, it played out as a wrote it - I offered some solutions to the problem and thought about different ways to solve it, then implemented the one I thought was best on the whiteboard. About halfway through he asked me why I wasn't implementing the best version, so I thought some more about it and couldn't come up with an in-place solution (which is very hard to find in an interview setting), so I continued down the same line when he wouldn't give me any help. After the interview his feedback to the manager (which I received because this was through a referral) was that he expected me to have this algorithm memorized and he gave me a "Strong No Hire" because I couldn't give the best solution.

Its worth noting that I received offers from over 50% of companies I interviewed at and I certainly am not bad at coding - this was just a particularly bad interviewer using a very bad problem. With this company, I actually told them I wouldn't accept an offer even if they did give me one because the interview was so bad.

Sounds like you dodged a bullet in that case :)

You had a hint that there was an in place solution and a set of pointers. I mean the only real question here is how many spots you need to look ahead...

I understand that whiteboard can be frustrating and hard, but it sounds like your interview was the exact kind of interview people try to make

It really depends what type of candidate you are looking for and what sort of job it is. One of the often overlooked roles of a hiring manager is understanding the signals coming in from the interviewers, weighing the results properly against other information, and making sure that the interviews actually gave information which can correlate to on the job performance.

In the past when I've been the hiring manager, I've had inexperienced interviewers ask my candidates questions like this for all kinds of positions - when you look at who does well in other interviews and gets an offer (and performs well), it basically never correlated at all to performance in whiteboard-only CS-focused interviews.

In this case I was interviewing for a full-stack senior position where there would almost certainly be zero systems-level coding, so the interview should have been a throwaway at best.

The point is that interviewers should not be looking for a "specific" answer. They should be looking for how well a candidate matches the expectations of the position. Asking for specific algorithm implementations is objectively bad interview practice.

So, it sounds like the candidate was interviewing for a senior engineering position and was given a problem to reverse a linked list in place. This is an entirely reasonable constraint and something that you would expect someone in a senior position to be able to do.

Space constraints do come up frequently and being able to reason about them is important.

I still maintain that asking for specific answers is a bad interview practice. It's a sign of a poor interviewer, not necessarily a bad candidate. It could be both in this case, but I'm talking about it at a more meta/higher level. IMO, it is objectively BAD interview practice being described here.

I don’t mean to be rude, but there’s no non-obvious “algorithm” for reversing a linked list in-place. If you can keep the details straight, you’re done. If a candidate had trouble with this problem, that would tell me that either 1) they have difficulty working at a fine level of detail, or 2) they aren’t comfortable with pointers. Either possibility is problematic for jobs that require attention to low-level detail or manipulating pointers or references.

I think the interviewer may have been a bit standoffish because he/she was expecting you to work out how to reverse a linked list rather than memorizing the algorithm.

My CS degree only taught me what a linked list is, not how to reverse one.

It's not a great question to ask because it's such a common one and many people will have learned an algorithm from a text book, but if you haven't memorized the solution it's simple enough to understand the requirements yet difficult enough to work out that you can get a good amount of insight into how a job applicant can solve rather than memorize problems.

After all, being able to separate candidates who can solve unseen problems from those who can't is one of the goals of interviews

Wow, that screams gatekeepers. If you are interested in doing an interview for my blog, https://www.nocsdegree.com let me know :)

I dropped out of my computer science degree program in 1993.

> Every single place except for one asked me about college or why I dropped out.

In the 26 years and 8 companies I've worked at since, along with hundreds of interviews, I've never been asked that question. In fact, my educational background has never come up.

Granted, 26 years is a lot longer than 8 years, but I'm quite surprised to hear your report. 8 years is, objectively, a good bit of experience.

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