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Dark Motives and Elective Use of Brainteaser Interview Questions

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Re: Dark Motives and Elective Use of Brainteaser Interview Questions

#281

Post by kitanata »

manish_gill wrote: post #50

I took an interview today and was asked a simple problem which I immediately answered with linear time complexity. The interviewer then went on to say "no I'm looking for a specific answer which involves a trick". Literally said those words. Eventually figured it out but I came away with a bad impression of the company. Not the kind of stuff I judge people on.

I had a similar thing happen when interviewing for ShutterStock 2-3 years ago. Wanted me to implement fibonaccci sequencer. I of course, forgot the mathematical definition of Fibonancii sequence, so went to Wikipedia to look it up. Was told I couldn’t use outside resources, then was told to think through what that sequence does and struggled a lot. Finally got through it with a really terrible recursive implementation, because the interviewer kept interrupting me and correcting me over the course of the interview, which took about an hour. I asked the interview where they put my skill level and I shit you not they said entry level to junior. I’ve been programming for 10 years at that point, and was significantly qualified for the position. After the interview was over, looked up a constant time formula based on the Golden Mean (from Wikipedia) and implemented a constant time algorithm to solve it. Took 4 lines of code and 10 minutes to do (including a test suite) Sent it in via email, and basically told them why their hiring process is broken and insulting to candidates.

I didn’t get the job, thank god.

Re: Dark Motives and Elective Use of Brainteaser Interview Questions

#282

Post by csense »

I think this particular question (a so-called Fermi problem) is a perfectly legitimate interview question. Being able to do "back-of-the-envelope calculations" is a necessary or helpful skill for many technical and analytical jobs.

It's not about getting the right answer, it's about the candidate's process to arrive at the answer.

Re: Dark Motives and Elective Use of Brainteaser Interview Questions

#283

Post by taurath »

guelo wrote: post #216
commandlinefan wrote: post #130

Earlier quoted context omitted.

> Some jobs require performance under pressure, but programming is not one of them. In fact, programming under pressure is the leading cause of programming disasters. It's the exact opposite of what a rational employer should want.

Not to defend that interviewer, but sometimes it's inevitable that you do have to code under pressure. I've been in situations where the whole system is collapsing, thousands of dollars are being lost every second, and I have to push a patch to production as quickly possible. Not that I would interview for such a situation.

And if you are in that position, it is because you have the most (or enough) context to be able to solve the problem.

In an interview situation, it is like being asked to fix a problem with skyscraper having never seen the interior before. Interviewing is low-context. You cannot test whether someone will fail under high-context pressure in an interview.

Re: Dark Motives and Elective Use of Brainteaser Interview Questions

#284

Post by taurath »

spython wrote: post #2

This reminds me of Jewish Problems[0], designed to "prevent Jews and other undesirables from getting a passing grade" at the entrance exams to the math department of Moscow State University. [0] https://arxiv.org/abs/1110.1556

As a self-taught programmer that has had to go back to get "cs fundamentals", half of interview questions feel like that - if you just know about x or y data structure for this particular edge case, everything becomes simple/easy.

Re: Dark Motives and Elective Use of Brainteaser Interview Questions

#285

Post by darawk »

ubernostrum wrote: post #267
darawk wrote: post #213

Earlier quoted context omitted.

I think that's the point of the question: to see how you approach it. The 'correct' approach that they'd be looking for is 'Fermi estimation': https://en.wikipedia.org/wiki/Fermi_problem

No, the point is to try to rationalize cargo-culting. Fermi did this, and Fermi was brilliant, so if we require candidates to do this we'll end up hiring people who are as brilliant as Fermi! Here's a brainteaser: spot all the flaws in that chain of "reasoning".

Um, no. It's not cargo-culting. It's the correct way of estimating things. It has nothing to do with Fermi having done it. Some things actually have correct answers. 2 + 2 = 4, is not cargo culting.

Re: Dark Motives and Elective Use of Brainteaser Interview Questions

#286

Post by groby_b »

spitfire wrote: post #105

Hunter and Schmidt did a meta-study of 85 (now 100, with the follow up) years of research on hiring criteria. [1] There are three attributes you need to select for to identify performing employees in intellectual fields. - General mental ability (Are they generally smart) Use WAIS or if there are artifacts of GMA(Complex work they've done themselves) available use them as proxies. Using IQ is effectively illegal[2] i…

Link [1] is borked. Presumably, this one works: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.172...

Also, you're missing the structured interview component.

Re: Dark Motives and Elective Use of Brainteaser Interview Questions

#287

Post by rumcajz »

dogecoinbase wrote: post #238
pzh wrote: post #118

Earlier quoted context omitted.

Aren't the examples of brainteasers actually Fermi problems? Maybe they sound like brainteasers if asked without the appropriate context, but when you're doing a system design interview and you have to estimate your throughput or storage requirements, you're effectively solving a Fermi problem just like the one that asks you to estimate the number of windows in NYC.

I love the term "Fermi problem", because the origin is, of course, the Fermi paradox. The idea that multiplying a series of uncertainties together does something other than blow your error range out is such a weird idea.

Related: https://arxiv.org/abs/1806.02404

Re: Dark Motives and Elective Use of Brainteaser Interview Questions

#288

Post by ubernostrum »

darawk wrote: post #285
ubernostrum wrote: post #267

Earlier quoted context omitted.

No, the point is to try to rationalize cargo-culting. Fermi did this, and Fermi was brilliant, so if we require candidates to do this we'll end up hiring people who are as brilliant as Fermi! Here's a brainteaser: spot all the flaws in that chain of "reasoning".

Um, no. It's not cargo-culting. It's the correct way of estimating things. It has nothing to do with Fermi having done it. Some things actually have correct answers. 2 + 2 = 4, is not cargo culting.

You just moved the goalposts from looking for "a Fermi estimate" to looking for a correct answer.

Re: Dark Motives and Elective Use of Brainteaser Interview Questions

#289

Post by Izkata »

pmiller2 wrote: post #189
spitfire wrote: post #105

Hunter and Schmidt did a meta-study of 85 (now 100, with the follow up) years of research on hiring criteria. [1] There are three attributes you need to select for to identify performing employees in intellectual fields. - General mental ability (Are they generally smart) Use WAIS or if there are artifacts of GMA(Complex work they've done themselves) available use them as proxies. Using IQ is effectively illegal[2] i…

What sort of meaningful work sample test can you do in 3 hours?

A year or so ago, one of our devs got some questions on our test replaced with things of the type the maintenance team occasionally gets asked, instead of making it solely about development and bugfixing, though twisted a bit to be feasible in an interview test (for example, the source data they'd work on was something like a 3 MB JSON file instead of a database).

Questions involved figuring out how to manipulate that data, and since not a single one could be done solely with a library call it said a lot about their ability to think through a problem, as well as their knowledge of things like data structures and efficiency. The latter questions even built off of the earlier ones, as if the stakeholder came back with more questions.

With a reasonable knowledge of the language you were using, those questions would only take around 15-30 minutes total, and each answer (as long as you did correctly build on the previous ones) was only ~5-10 lines of code.

Re: Dark Motives and Elective Use of Brainteaser Interview Questions

#290

Post by stevenwoo »

jacquesm wrote: post #167
jkingsbery wrote: post #149

Earlier quoted context omitted.

TRUE STORY: I interviewed at Google earlier in my career. In one of the interviews, the interviewer asked me to recite/reconstruct off the top of my head the convex hull algorithm. I remembered the lectures in undergrad algo class where the professor talked about it. I remembered where in CLRS it was covered. I remembered the general outline (efficient algorithms are O(n log n), because you have to sort the points as…

> We expect Google engineers to be able to solve problems. Sounds more like he expects Google engineers to have perfect recall, rather than to be able to solve problems. That's just a trivia question, nothing to do with problem solving.

If I wanted to have a job that required perfect recall, I would have become a doctor. Maybe I should have if that is what this industry is going to require.
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