The annoying ones are dudes who want you to somehow do a big O proof of some NP complete problem, with tests, proper code, and in front of 3 people in 45 mins (with 5 left for you to ask any questions). For something you may have not touched in 20+ years. I do not want a guy who can create the proof. I want a guy who can explain it in plain English to the 3 other guys in the group and maybe take a few days to get it right and make the code easy enough to understand so when we have to change it in 8 months they can pick it back up.
I have worked in the embedded industry for 6 years, and have worked on a wide variety of projects (from WiFi to drones/airplanes to medical devices), and have never needed to use this, yet the interviewer expected me to know this.
Anecdotally speaking, when recruiters throw this kind of curve balls, it's because they already have someone in mind for that position and are interviewing candidates just to fill paperwork.
Some people ask more clarifying questions than others, but in any case a few minutes gets spent on this, we have a laugh and move on with our lives.
Of the failing candidates, around one in three or so spend nearly the entire interview on this or fail to answer entirely because they can't get the maths right.
Is that a "math trick"? It doesn't feel too different to fizzbuzz. It's not complex. It relies on high school maths, and except for very junior positions, for a job where you are expected to solve much more complex problems every day without handholding, even if you can't remember how averages work so I have to hand you the math, not being able to reason through the problem from first principles seems like a pretty big red flag for your problem solving skills to me.
What do people think?
Once I show someone the 'mod' trick they instantly get it (if they have any sort of math background) but I want to avoid as much as possible anything tricky in a interview. I want them relaxed and not tense. As that is a different kind of test. Throwing in a trivia trick can hurt the interview. I have run across many programmers that are decent at it and have never used it.
Also for your problem it would depend on the level you are interviewing for and how much time you want to allocate for it. As it is also a balance of filter and getting to know them which is mostly time management on your part. Remember you probably are going to be working with them. So a bit of chit chat goes a long way too. You can also use 'fizzbuzz' as a question 'do you know the trick of fizzbuzz'. If I show them the mod trick and they get it right away they show aptitude to learn. If they already know it then see if they can explain it. etc etc... Get them to talk. Also talk back to them like a peer as they very well could be! They should be interviewing you too.
I just try to avoid tricky bits in interviews and expecting tricky results from them. It would be like asking the to write a swap two values function and expecting the triple xor solution. Tricky is for something you have been working on for 3 weeks and need a better solution, plus two spike stories. It is not for interviews. :) Just ask yourself would you be massively annoyed if someone asked you this in an interview with no context as to why and expected a particular answer. If the answer is you would be annoyed then do not do it. If you feel it is OK and you would expect it then go for it. Just remember your time management.
But if you are applying for a programming position and claim a decade of programming experience - and literally can't come up with any path towards a solution - I smell a rat.
Honestly, the latter guys are absolutely fire to work with. I think recruiting is like security engineering: 90% of the guys doing it are total rubbish so you just assume that's what it's like. But that last 10% are super good, and the top 1% are really freaking good.
I remember when I first encountered a recruiting pipeline put together by a guy who was good at it. Literally every person I spoke to was a good engineer. We did tech-screen them, but only after the initial call where we talked to them about their interests and our company objectives.
Literally every one of these engineers knew:
* What sorts of problems they wanted to work on
* What stage of company they wanted to work at (seed, series-A, ..., big established company)
* What risk they were willing to take
* What sort of team they wanted to work on
This may not be scalable at Google/FB where you're hiring commodity L3-L5s a lot.
Anyway, I was very impressed. Also, the fact that almost every one of them didn't bat an eye at the tech screen. You read some of the comments on HN/Reddit and you see that these guys are a cut above the standard dudes.
Like, just the social nous. Way off the charts. On HN, people talk about an interviewer mis-sizing the problem: "Haha, so I told him I'd do it on a single SGI UV 300 with 3 TB of RAM. The interviewer got stuck. I got him.". These guys are like way better. If you mis-size, they'll just be like "Ah, okay, so you can get this done on a single machine these days, they have a lot of RAM, but that's trivial. AWS has the u24s for 24 TB or something. So let's say the problem is even bigger or that we want the other advantages of clusters" and they'll take it away. No chip on the shoulder. No insecurity. If some constraint doesn't make sense, they'll say "Okay, if we were doing this in prod, I'd push back on that, but let's say it's the case" and just go on.
We didn't convert everyone - not everyone wants to work in our domain or wants to deal with the quirks of our team or whatever, but that's life. It was way more enjoyable as an interviewer.
I think that's probably more the rub than anything. I never had a happier time being an interviewer than my time at hypergrowth startups. The sheer caliber of both candidates AND resource allotment towards landing them was far higher than what I was able to see in the BigCo environment. It made things a lot more pleasant.
I'll give you a pro-tip: Candidate Interview Packs. Cook up some Google Slides with the main info about the position, the company, the team, what you expect from the person, what you are looking for, the interview process, etc; beyond the dry JD that HR shares. Give it the personality of your (Engineering) team and generate a PDF that you can share with the 50+ candidates.
It has worked for me in the past.
Don't get me wrong-- I've worked with very incompetent people. Many of them would have passed a coding interview though.
I've interviewed enough people who don't even know the syntax of a for loop for the language that they chose to use.
As a general matter for how the industry as a whole interviews, I agree though; I am no longer a fan of tricky algorithmic or esoteric data structure questions in whiteboard interviews. The problem I find with other people's interviewing questions is that most people are still asking things that are way too difficult, and they don't end up judging anything other than "Did this person just cram hundreds of hours of algorithms questions?" or "Did this person get lucky and happen to know this type of problem ahead of time?".
For better or for worse, my company schedules me for like >90% system design questions now, which I prefer anyways. Start with a very simple problem and system, and then just throw wrenches.
Most loops are covered by a foreach or by LINQ (think: map and reduce, buy nicer).
The few times I actually need a for loop I type: "for" <press enter> <type the limit for i> <press enter> and then I focus on the loop body. If my needs are more complicated, I _modify_ the for loop my IDE gives me.
However, the particularly insidious candidates are the ones who have developed a skill for talking about software/programming but can't actually write code no matter how much help or prodding they are given. As soon as you accidentally hire one of those, the case for technical interviews becomes a lot stronger.
Once he joined the company he proceeded to actually be completely unable to write a single working piece of code. Everything he wrote needed to be reviewed and had major glaring issues. When confronted about it, he would say that he couldn't figure it out so decided to just commit his unfinished code.
That guy was senior, had worked for 20 years and is really good at talking but when it comes to actually developing software, he is completely utterly incompetent.
I've had candidates who seemed incredibly accomplished when talking them, who showed amazing looking demos and could talk at length about them. But when given a task to do on the computer, given 2 hours alone to sit and code, couldn't do even the first part of the exercise - despite it being something you could literally copy and paste from the documentation that we gave them a link to!
I think the type of problem and structure we use for interviews is bad. Let the candidate code alone without you watching. Give them internet access. Come back in an hour or two, or let them do it remotely or as a take home. This is more like our real jobs; and gets rid of cutesy "do you know this algorithm?" questions, which many whiteboarding problems are. Instead of going for pure data structure / dp / search / sort algorithms, have them implement things like business rules.
The problem's not even that I'm bad under pressure, and in fact I've repeatedly been told the exact opposite by people who've worked with me. The problem is specifically about doing a programming performance in front of an audience, in an interview rather than co-worker context. I'm god-awful at that unless I'm heavily prepped for exactly what's going on. No tools? I'll forget basic syntax, yes even in "a language I chose". Let me use tools? I'll forget how to use them, or get self-conscious and avoid things I'm not entirely sure will work, overriding my own muscle memory. It's a very specific problem but I doubt I'm the only one who absolutely can do the job just fine, but is also entirely capable of coming off like a complete "faker" in an interview.
[EDIT] to make matters worse I can talk about programming just fine in that setting, which probably adds to the "he's some kind of social engineering genius who learned to sound exactly like a competent programmer while somehow also not learning a single thing about programming" impression. It's not usually an issue, but I'm quite sure I've reinforced some interviewers' notion that it's a good thing they do whiteboard screening because they're overwhelmed with lying applicants, and that I was one of them.
I've met one developer who couldn't do their job, and he moved into a pre-sales role shortly thereafter.
Everyone else was fine and did a good job but send them unprepared to a random interview on any given day of the week and I'm sure it'd be another one of those "well we dodged a bullet there".
The signal to noise ratio is Garbage.
Sure a "whiteboard interview" basically optimizes for people who can actually pass whiteboard interviews rather than people who can do the job.
But to claim that there is a NON-NEGLIGIBLE number of people who basically become 100% ignorant when under the stress of a whiteboard interview BUT are excellent employees in any other stressful situation is, to say it in nice words, [requires citation].
And if one really has this apparent rather unique type of handicap, then better mention on CV to try to get some empathy from the hirer, or just _train_ to avoid it. Yes, most people do _train_ for the express purpose of passing interviews.
Tech interviews are remarkably scattershot in the form they take (outside well-known big companies), and are unusually anxiety-generating, even in the notoriously anxiety-filled field of interviews. Describe what one might (emphasis on might, part of the problem is that it's so often a surprise) expect in a tech interview process to some people outside the industry, and gauge their reactions. I definitely think it's likely they have even worse signal-to-noise ratio than is commonly thought.
[EDIT] Certainly I find it far less plausible that there's an absolute army of people out there, dwarfing the count of actually capable programmers, who are brilliant con-persons but too dumb to figure out that that skill itself is more valuable than programming, outside the top couple percent of programming jobs by comp, and apply it more directly to business roles that actively want it.
And I'm quite confident it's not the interviewer. Usually the panel is quite anonymous when it comes to calling a "bullshit" candidate. We ask panel persons individually to avoid the "no one wants to contradict someone calling X bullshit'" effect.
I don't think tech interviews are _any_ worse than the ones outside. If anything, we have less standardization than other industries. I work for a engineering company first (software second) and the engineer interviews are basically _manufactured by HR_ (not engineers).
In this scenario, having someone literally be unable, in 2 hours, to replicate the first example code of some library, when they have access to almost identical code in the docs, is a pretty good filter.
The problem is when you apparently _forget_ the syntax for a function declaration in a programming language you claim N years of experience in your CURRENT position. This is just absurd. Our you suddenly get completely stuck with counting odd numbers on a sequence or the like. And this happens surprisingly frequently. I just cannot believe you can have this type of anxiety (I am extremely shy myself) outside your first or maybe second interview.
Languages like C that have a single official for loop syntax are a bit easier to remember, in part because it's a syntax I have previously used on a whiteboard rather than exclusively in actual code.
So if a candidate can't write a loop on a whiteboard, maybe let them try in a non-IDE text editor, or have them glance at a formal grammar for the language as a refresher that won't give away the game to someone who can't actually code.
And if I start showing them an EBNF grammar for the language, now that's TWO languages that you will show you don't remember rather than one. I find this even more absurd; you don't remember anything of the syntax of the language you used at work for years, but you think you can rediscover it from the FORMAL language specification in a whiteboard?
This is it, in a nutshell.
In all my years of interviewing candidates, I've never run into the mythical experienced developer who doesn't know anything about programming. Yet according to HN lore, there are hordes of them out there.
My theory is that the only thing there are indeed hordes of, is experienced developers who can be made to look dumb by subjecting them to whiteboard puzzles, algorithm trivia and other such questions which are completely unrelated to the job performance.
It's too true. A quick search found the source article that I read years ago here[0]. :)
From that page:
> We can't understand why so many people "fail" the Fizz-Buzz test unless we understand why it is "hard" (for them).
But the article doesn't even talk about the environment, which is what it's all about.
It's hard "for them" because they're being asked to write the code on a whiteboard, with a job/income on the line, with stress and anxiety dialed up to 11, with someone breathing down their neck watching, while expected to simultaneously provide cheerful ongoing commentary to "show how they think".
Under those conditions, I totally believe close to 100% perfectly competent developers will fail at it. But of course it has nothing to do with the programming part.
Most of us have heard of FizzBuzz while chillin at home reading articles and immediately thought "that can't be hard" and tried it and indeed it is laughably easy. So we can't understand how "they" could fail at it because we didn't experience it under interview hazing conditions.
So the "them" is actually all of us.
To me that is the key takeaway of FizzBuzz.
Of course the tests are proxies and often aren't even scored objectively. And most tests aren't very good at proxying anything general (hence companies' tendencies to have several). There's a lot of problems that remain, our industry doesn't take hiring seriously. But testing and trying to test as early as possible have come to dominate for not totally unreasonable reasons, and persist at the large companies despite the well-known negative trade-offs. It's a startup's/small company's advantage to not copy bigco's interview processes.
Why? IMO this is about an order of magnitude too many. I typically interview about 3-4 people, on rare occasions a few more. I've been interviewing candidates for about 25 years now.
If your recruiter is sending you 50+ mismatched resumes for a role, get a better recruiter. But even in that case, you should notice and weed these out while reviewing the resumes yourself, before getting to the interview stage.
I literally cannot imagine any scenario where I'd interview over 50 people for a role. Or even ten people.
A few startups ago we had to grow the team from 20 people to ~120 in a year. Your approach would result in interviewing well over 5000 people in a year. That would be over 20 people a day, every single day, zero work getting done meanwhile! I suggest a re-think of your hiring strategy.
> being obviously unfit after the first 10 minutes of a technical interview
Which one is more likely:
1. Senior people who have built many successful products don't actually know how to do what they've done.
or
2. Interview techniques that focus on skills unrelated to the job (e.g. whiteboard puzzles, algorithm trivial pursuit) have an inordinately high false negative rate.
I ask because 50 is not completely unreasonable. I've had positions where we've had to interview dozens of candidates, in our small company. In larger companies, often someone else does some initial interviews though and that filters out candidates who e.g. can't code at all (sometimes - not always!).
Like I said, I think if you have to interview that many, your filtering process is really broken further up the pipeline. You don’t know what you want, what the job really is, the or application process isn’t properly structured.
Interviewing large numbers of people is also a huge liability unless you’re extremely consistent and well-documented in your hiring process (something which I’ve found to rarely be the case).
I interviewed at Google. The position description versus what I was interviewed on were two worlds apart. Like the position mentioned front end CSS and HTML. I was grilled on SQL in two of the 4 interviews. This wasn't a SWE position, it was more of a client support role, but I was given a coding test. I did poorly on the test, but I still consider it difficult for a role that was not a SWE.
It didn't even seem like Google knew what role they were hiring for they just wanted "someone technical" to do something. I left this process feeling pretty confused and turned-off at their hiring process and questioning if I really wanted to work at a place like that.
Let me clarify first that 50 interviews include phone screening, where we don't do specific technical questions but rather just poke around what the candidate is looking for and whether they seem able to explain what they have been doing without drowning.
As for the process we use, we are a hedge fund of 30 people, we have no HR, so I directly deal with head hunters. That means the numbers I gave are "raw".
I see a lot of comments arguing whether it's even possible to assess technical skills during an interview, and overall spitting on whiteboard brain teasers.
For the former, really, you need to be in the front row of hiring to understand it. I'm not talking about filtering candidates that can answer library specific trivia or solve red black tree removal on a white board here. I'm talking about senior Python developers that cannot remember the syntax of a for loop, data science specialists that cannot ELI5 the intuition of a linear regression. That's the degree of "low skill level" I'm talking about. I think a lot of people here are biased toward thinking the average programmer on the market should be the same skill level of their average colleague.
This is Wrong.
You are reading hacker news, you are very likely to be passioned and dedicated about what you are doing, you are most likely working in an above average company, surrounded with above average colleagues. Your perception of the average programmer is biased toward your own surroundings.
Now I see that the whiteboard interview seems to be really dreaded. And man, do I feel you. I also used to hate them as an interviewee. But that does not mean they are all the same.
When I do a whiteboard interview, I am perfectly aware that the candidate is obviously stressed, uncomfortable, and not at 100% of his potential. That's why the questions I ask are typically not too intellectually challenging. Some variations of the fizzbuzz mainly, along with a small exercice on recursivity in case the fizzbuzz is too easy.
"Whiteboard interview" should not become a strawman for "24yo fresh grad throws B-tree inversion at you to feel superior". Really, the only thing that should be tested in these interviews is your programmer muscle memory. And from my experience, it does work.
I would think that any "straight to the point" hiring process would be "straight to the point" because it avoided the technical interview process:
A) there's not much you can do to entirely avoid problems with work performance and B) technical knowledge can only be sussed out so far in an interview, period, before actual work performance in the context you're hiring the person for can be evaluated.
The thing is, when you look for a job, you will often go for 5 to 10 interviews.
On the other end, when I'm looking for someone to fill a position in my team, I will interview at the very least 50 candidates.
That is to say, all things equal, the interviewer has most likely more incentive than the interviewee to go straight to the point, and thus perform a technical check early in the process.
Also, you have to realize than the vast majority of candidates applying for a position are highly unfit for it. Seriously, even for very senior positions, you would be amazed at the sheer amount of people applying with grossly pumped resumes, and overall low skill level once tested.
Even after careful picking of resumes, I would estimate that 80% of candidates end up being obviously unfit after the first 10 minutes of a technical interview. That's why, as an interviewer, I'm not very inclined to have a long open discussion about the job until I have at least some degree of confidence that the candidate is worth it.
Of course that process is unfair for the "good" candidates. Those who apply to positions fitting their skill set. But when you have more than 50 interviews ahead of you, and an actual job to do, you have to make compromises and tailor your process for efficiency.