The Hardest Interview Puzzle Question Ever

@Swizec: Please, tell me you’re not the Swizec who authored an article called something like there’s no such thing as a stupid user?

The moment I read that question about soda I rushed into the comments with Zero! I don’t like any soda, so the exactly right answer is zero! And, naturally, there was a lot of answers like that already, and now my day is ruined…

Here’s a good answer to the Mt. Fuji question: http://angryaussie.wordpress.com/2007/11/01/pointless-interview-questions/

@Will:

Actually, my favorite soda is Moxie (look it up, boys girls), so unless the interview is taking place in New England, the answer is statistically close to zero.

Come to think of it…that answer might apply in New England, too.

I remember figuring out over a coffee break how many coffee swizel sticks we’re likely consumed on a daily basis in Canada.

We figured it was about a cubic meter’s worth.

How much of your favorite brand of soda is consumed in this state?

I don’t drink store-bought, so my favorite brand would have to be the stuff I brew in my kitchen. In the past year, I’ve made 2 5-gallon batches, so I’d have to say: 10 gallons. Pretty good margin of error on that figure, too. :slight_smile:

I once didn’t get my dream job because they had some mental maths thing that we all had to pass.

I hadn’t done the four fifths of 22 means it’s Tuesday stuff in 20 years and couldn’t do it without a lot of practice. If they’d asked me to do a presentation, or some questions about programming and project management I’d have had a fighting chance. I can do most of the programming problems without any prep - been doing it 22 years.

It was also very ageist, I don’t do those kind of puzzles. I got my degree (1987) when most of the people in the room weren’t even zygotes, if I’d had this kind of quiz then I would probably have aced it. I got a very high mark on the Java Certification exam, but that was because I studied for it. There was no way to practice for this kind of thing. In retrospect I’m glad I failed, because they must be idiots if they think it makes any difference.

Just a lazy way for the Human Resources (erm - I’m a person, hello??) to sieve people and be ageist without appearing to be. If they ask questions like that it’s because they have nothing useful to do. Plus it cost me a train ticket to London, and they ain’t cheap.

http://www.xckd.com/554/

What i generally dislike about puzzle questions is the ambiguity, some element that you’re not told and that you have to assume. It’s like being asked 100 questions at the same time.

Assumptions are critical and it’s the first thing you try to work out, so being told to assume without consequence… i think it’s a little pointless.

How well can you judge someone’s thought process given that their assumptions are arbitrary? How much can you take from it?

Good Communication != Good Nurse

I get what you’re saying with your recent nursing experience. I also agree that you cannot be an exception nurse (or programmer) without good communication skills.

Having said that, I would much rather have a nurse with sound medical skills helping my when I’m going into cardiac arrest then one who is friendly but cheated through nursing school. Likewise, I would much rather have a programmer with exceptional programming skills design the airbag system in my car and tells the worst water cooler story ever.

In conclusion, the worst nurses were invariably the worst communicators! only means that they are bad communicators. Maybe you can conclude that they are not exceptional nurses…

Now, hopefully, I communicated my point well :slight_smile:

10 bottles of possibly poisoned wine? Clearly the prisoners are all ninjas.

3 PIRATES VS. 100 NINJAS! All other data is irrelevant.

It’s nearly ubiquitous to force PhD level applicants for academic/science positions to do a job talk – a one hour presentation/seminar on the subject of their thesis. After all, the applicant is someone who has just spent years working on one topic, and they ought to have something interesting to say about it.

Having been to many, I can safely say that ten minutes would probably be enough to judge their abilities, but it would be unfair to them to force 5 years of work to be summarized down to such a short presentation.

I guess academics do something right, then, even if they are long-winded about it. :slight_smile:

As someone who poses interview questions a lot (and answers them rarely if ever) I must tell you, they are really important. Until we are allowed to give candidates IQ tests they are the best / only way we have to form an estimate of how smart people are, in the sense of how they think. And the interaction of working through a puzzle together gives you a chance to see how they think, how they problem solve, and how they handle stressful situations.

I like programming related puzzles (how would you model a pool table) and abstract questions (how many pathologists are there in the U.S.). They have to be solvable, by the way; questions which are too hard don’t tell you anything. And questions which involve some kind of trick don’t tell you much either.

Cheers…

I hate puzzle questions too. At one point it became fashionable where I worked to post puzzles on the noticeboards outside your office. For awhile mine was:

e = 3
n = 343285878569830523580893306575740679545716377525420211495576158140025012622859413021647155097925923099079654737612551765675135751782966645477917450112996148903046399471329621073404375189573596145890193897131117904297828564750320319869151402870808599048010941214722131794764777262241425485454033215718530614228813758504306332175182979866223717215916077166925474873898665494945011465406284336639379003976926567214638530673609657120918076383271664162748888007869256029022847210403172118608204190004229661711963779213375751149595015660496318629472654736425230817703675159067350235072835405670403867435136222247715891504953098444893330963408780769325993978054193414473774418426312986080998886874132604721569516239658645730216315981931951673538129741677294786724229246543668009806769282382806899640048243540370141631496589794092432378969070697794223625082216889573837986230015937764716512289357860158816175578297352334460428151262720373431465319777741603199066554187639792933441952154134189948544473456738316249934191318148092777710386387734317720754565453220777092120190516609628049092636019759882816133231666365286193266863360627356763035447762803504507772355471058595487027908143562401451718062464362679456127531813407833033625423278394497538243720583531147711992606381334677687969597030983391307710987

What is p and q?

(Oh, and I doctored other people’s puzzles to make them unsolveable. At least mine’s solveable).

… and I’ve just messed up the formatting on Jeff’s page (sorry :-). In compensation I’ll give my response to the Moving Mt.Fuji question, which is (a) how far do you want to move it, (b) how quickly do you want it moved, and © how much lithium-6 deuteride can I use in the process?

Agree completely about how useful this style of interview question is. I can sort of see why they might be considered useful in allowing candidates to demonstrate their reasoning skills, but it must surely be much more relevant to give them an actual computing problem. Showing a spec and asking how to go about implementing it would demonstrate the same skill sets in a way that would be far more revealing.

But I donít agree with the 10 minute talk either. Even if you consider communication skills to be the most important trait of a programmer, surely the interview itself will tell you all you need to know about the candidateís relevant ability. A presentation is an entirely different type of communication, and one most programmers do not need.

I hate guessing questions. As a military officer I was trained to never guess. In one of the briefings I was present at, one of the officers asked a bunch of us cadets how deep we thought a stream was in the middle of the map. He listened to a half dozen people and then had us vote on how deep we thought the stream was. Everyone that had guessed a specific depth without any facts was then forced into a front leaning rest position and screamed at by a half dozen officers how they had just killed their entire unit because they f*ing guessed. Lessons like that stick.

They are good for engineering jobs.
The ‘trick’ ones about telling the color of your own hat or the two guards in front of doors are useless - everybody has heard them.

But the how much does Mt Fuji weigh questions are good. I expect a civil engineer to be able to estimate rock mass and I expect a software engineer to be able to estimate I/O rates or how many clients a server can handle

Until we are allowed to give candidates IQ tests they are the best / only way we have to form an estimate of how smart people are

@Ole
My question is do you really think an IQ test would realy show how a person thinks, or how qualified they are for a position.

I think asking questions that are related to the scope of work would give you a better indicator to what skills they have to do the job.

I agree that comunications skills are very important when you hire architect

The answer is Blue. NO! Yellow.

I have a genius-level IQ and I hate with a passion stupid interview questions of the type that Jeff is mocking.

They don’t get you anyone except those that are interested in mental masturbation, which is the type of people that they are also given by. But what they DON’T do is further the bottom line.

People that think these questions are good are exactly the type of people that spend weeks investigating a problem instead of just saying, Oh, well, Microsoft has a bug but we can work around it by adding a /table tag. And for everyone that just cringed when I said that, realize that your employer usually doesn’t care if your website validates as long as it works on the 2 latest versions of IE and Firefox. And he WOULD RATHER that you not spend $10000 of his money figuring out how Microsoft screwed up and making a blog posting about it. He would rather you rolled the website out yesterday so that he can make more money.

A few people (including Jeff) have it right. Computer knowledge is always changing, so why bother testing people on that? What you want to know is:

  1. Are they a good person and a good communicator?

No matter how smart or how good a coder someone is, if they are an island that can’t communicate, you will end up rewriting their code when they are gone and they will cause friction in the office, because people will always be wary of them and their motives because of the lack of communication (as Jeff pointed out regarding the nurses). Also, you don’t want harrassment lawsuits or theft, so try to make sure the person you are hiring has some morals.

  1. Can they learn?

This career is all about learning. There are new things coming out all the time. I was actually turned down in a job because I didn’t know something that was still in Beta in Visual Studio. That’s dumb. It’s not that I can’t learn the latest Microsoft technology, it’s that I haven’t been exposed to it yet because it hasn’t even come out yet. I’ve been busy adding value to my employer with solutions that work and are maintainable, not bleeding edge beta stuff that isn’t even licensed for production code yet.

  1. Past success is absolutely an indicator of future success

Make sure that the person can describe successes and failures in detail. Make sure they know WHY they failed and what steps they have taken since to prevent a reoccurrance. That goes back to learning. Also, listen to how passionate they were about their successes and make sure to find ones where they were involved.

For a technical question, stick to a broad topic not a specific command line option. Command line options can be looked up in 1 minute. Instead, ask them to describe the dangers of SQL Injection and how to avoid it or some other topic that good developers absolutely should know.

And ultimately, hire them on a trial basis of at least 30 days. If they aren’t working out (for instance, a person with a Masters in programming asking what comma-delimited is), don’t be afraid to let them go quickly, before they waste too much of your company’s money.

And before you assume that I don’t know what I am talking about, I helped hire most of the best people for a consulting company that has survived multiple recessions and wrote award-winning websites for the nationally-known industry leader in a certain vertical.

And we never used puzzle/IQ questions to do it.