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June 26, 2006

A World Cup Inspired Interview Question

In honor of the quadrennial soccer fest, I though of the following interview question.

As background, in the World Cup the teams are each assigned to groups with three other teams. They play a round robin against all the teams in their group. Teams are given 3 points for a win and 1 point each for a tie. The top two teams in each group, by point total, advance to the next round. So the question is:

Imagine that one team in a group earns 3 points due to having tied three games, and another team in the same group earns 3 points due to winning one game, and that they wind up tied for second place in the group. Which team has a better argument for deserving to advance?

I like the question because it reminds me of some programming design issues you have to solve, and people should be able to work through a solution pretty quickly.

Posted by AdamBa at June 26, 2006 10:43 PM

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You mean if it were possible? Because if team A draws all their games then the other three teams have at least one point from their draw with team A. No other team can have a win and two lost games.

Posted by: Don Speekingleesh at June 26, 2006 11:53 PM

Don Speekingleesh beat me to it - the scenario isn't possible. Is this a trick question?

Posted by: Dirk at June 27, 2006 12:42 AM

That is indeed the answer. It is a trick question, but I don't think it's an unfair trick. Any logical approach to it should quickly come to the question of "what happened when those two teams played each other?" and then the impossibility would appear.

- adam

Posted by: Adam Barr at June 27, 2006 08:26 AM

Great! Another trick question! How clever!

No offense, but do you honestly think that this kind of stuff filters out *only* bad engineers during the interview process?

Posted by: Flunked Out at June 27, 2006 12:40 PM

FO: Although I do not in general like trick questions and in fact flatter myself that I was one of the people responsible for getting them booted out of Microsoft -- in this particular case I will go out on a limb and say YES, I would be surprised if a good programmer did not figure this one out pretty quickly.

- adam

Posted by: Adam Barr at June 27, 2006 05:08 PM

Emmm... people that can answer this may not always be clever... I for one can answer this immediately because it has been discussed in one of the local TV show here... :P

Posted by: Cheong at June 27, 2006 08:41 PM

I'm not saying that everyone who answers it is clever, just that clever people should be able to answer it. That is the right bias for an interview question. You want something that a qualified person WILL get right and an unqualified person MAY get right. Do enough questions like that over the course of the day and you have a reasonable expectation of filtering out the unqualified people. People can prepare for a single question but over the long haul, the only preparation that will work is actually being competent (at least you hope that's true).

If there was one magic question that would be answered by 100% of the people you wanted to hire and 0% of the people you don't want to hire, you could just ask that one question and be done.

- adam

Posted by: Adam Barr at June 28, 2006 10:43 AM

That's not trick question. It is misleading question.

You are asking what would happen in case both teams get equal score. This is compleatly possible situation.

The fact that you gave invalid reasoning for the way these teams had reached equal score doesn't invalidate the question. It is not a mathematical problem that cannot be solved if the terms are wrong.

So yes, that was really dumb question for the person who is "one of the people responsible for getting them booted out of Microsoft".

I think that the question "Could you tell all the cases where 2 teams could come with same score" would be much better for interview in you care about permutation, combination and variation skills. And you could also change the number of playing teams.

Posted by: Ivan at June 29, 2006 01:22 PM

I recently interviewed with a large number of tech companies (Google, Amazon, Microsoft, Oracle, IBM) and was not once asked a puzzle/brain teaser (and I would consider Adam's question above a simple brain teaser).

That fad (or was it a trend?) has passed.

Posted by: adamp at June 30, 2006 01:46 PM

Interesting that nobody does brainteasers anymore. I suppose that means we need to start asking them again. I actually am considering reconsidering my position on brainteasers. Not the "unfair" ones, but maybe we are throwing the baby out with the bathwater. Brainteasers may be the worst kind of interview questions for Microsoft, except for every other kind.

Ivan, I am NOT asking what happens if two teams get equal score. I am asking a specific question which you should answer as asked. If during an interview you choose to answer a different question from the one I asked that is of course your prerogative, but it's my prerogative to slap a big "NO HIRE" on your interview feedback.

- adam

Posted by: Adam Barr at June 30, 2006 08:14 PM

(Sorry for the long, unbroken paragraph, but I don't know how to preserve formatting under MovableHype.)

This type of question filters for people who are intelligent AND test well ("think on their feet"). Is 'testing well' and 'thinking on your feet' a requisite for all software engineering jobs? Or, might this also filter out some fine engineers who are not the 'blink' (rapid responder) types?

I'll admit that this may be a valid filter for a given organization; it's just crazy to assume that you are filtering out bad engineers and nothing else. There are people (more than you may know or care to admit) who do not 'thrive' on stressful on-the-spot situations who are also capable of fine engineering work. (People who are vastly better at written communication than verbal for instance... will generally do poorly in a stressful, face-to-face situation - like an interview where someone throws abstract or trick puzzles at them.)

This sort of interviewing technique reminds me of the doormen at a trendy nightclub: You can't get in unless you dress right, have the right look, and fit the profile that the owners of the nightclub want to promote. Now, the nightclub owners have every right to enforce these policies, but they really ought to be aware that they are creating a monoculture. I assert that software engineering is not the same as what goes on in a nightclub... or is it?

Talk about killing diversity... Whatever happened to engineering as a sustained mental effort? When did engineering turn into a 'blink' activity?

Interviewing well is a difficult task, and I assert that one cannot reduce it to a formulaic system of throwing hard problems at people and watch how they respond - this is laziness taken to the extreme, and is indicative of a process that has broken down (for example, no need to spend much time reading a resume or digging into a person's abilities by looking at past history, all I have to do is throw a few puzzles their way and see what happens.)

(And yes, I'm one of the people who doesn't test well or think on his feet under stressful situations.. so I'm forever locked out of the trendy Microsoft [or Google] nighclubs. My attitude: You get, and have gotten, what you deserve.)


Posted by: Flunked Out at July 1, 2006 08:51 AM

Ivan, I was reading my response to you and realized it sounded a little harsh. I meant it as advice, not criticism. One mistake people make in interviews is to answer a different question from the one that was asked. They do this accidentally because they didn't understand it or on purpose because they think they can answer the other question better, but in either case the interviewer will notice. If you ask questions to clarify then that's OK, but you likely still need to answer the original question. Now, saying out loud, as an approach to the answer, "Let's first enumerate all the ways that two teams can wind up with 3 points" is one way to tackle it and likely will result in you realizing the "trick" in the original question.

FO, you make a lot of the points I made protesting brainteasers. I agree with what you say. And certainly Microsoft's old interview style had serious problems (although it was never (or rarely) "throw a few puzzles their way and see what happens"). NONETHELESS I am wondering if entirely removing them is the right thing. The question I asked above is a mild brainteaser that I think you can work through with a little thought. It's not a pure "Aha!" question like the three lightbulbs one.

The overarching thing I look at is that Microsoft used to use brainteasers as a component of hiring and the company's stock went up and up, and now we have stopped and the stock is flat. YES there are many many factors involved (the company is much bigger and is hiring a lot more people, for one thing), but still it makes me wonder.

- adam

Posted by: Adam Barr at July 1, 2006 10:57 AM