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Steve Ballmer's incorrect binary search interview question

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Re: Steve Ballmer's incorrect binary search interview question

#121

Post by rpdillon »

HarryHirsch wrote: post #58
ozim wrote: post #52

Earlier quoted context omitted.

What was the last time you were on the interview? I think like 70% of interviews I ever had were like they were there to prove how smart they are and how stupid I am. I suppose most likely to make me feel stupid and accept lowball offer.

Like this one: https://rachelbythebay.com/w/2011/07/27/ohreally/ Yes, that happens, and elsewhere she goes on about culture in tech.

I strongly agree with the sibling comment that this is a perfectly valid interview question.

One of the biggest red flags in an interview is if I ask a question and the person doesn't know how to say 'I don't know', because it suggests there's a big risk that if I assign them a task in their day-to-day work, they won't tell me if they feel unprepared to tackle it. That's a far bigger issue than not knowing that traceroute uses variable TTLs to figure out the timing along the route.

Re: Steve Ballmer's incorrect binary search interview question

#122

Post by jliptzin »

ozim wrote: post #52
enneff wrote: post #48

Earlier quoted context omitted.

Unless the interviewer has totally lost sight of the purpose of the interview, they’d recognise a candidate starting at an offset from 50 as an instant pass.

What was the last time you were on the interview? I think like 70% of interviews I ever had were like they were there to prove how smart they are and how stupid I am. I suppose most likely to make me feel stupid and accept lowball offer.

Yea, they’re pointless. The amount of time someone spends on a truly difficult and important problem is maybe 0.1% of their job. And usually it’s better to just call in a domain expert anyway if it’s something that important. The other 99.9% - do they show up on time and work hard, do they care about the company, do they fit in with the rest of the team, etc, mostly can’t be determined in a short interview anyway.

Re: Steve Ballmer's incorrect binary search interview question

#123

Post by enneff »

ozim wrote: post #52
enneff wrote: post #48

Earlier quoted context omitted.

Unless the interviewer has totally lost sight of the purpose of the interview, they’d recognise a candidate starting at an offset from 50 as an instant pass.

What was the last time you were on the interview? I think like 70% of interviews I ever had were like they were there to prove how smart they are and how stupid I am. I suppose most likely to make me feel stupid and accept lowball offer.

It’s been a long long time since I was interviewed for a job, but I have conducted a lot of interviews since then and any signal that the candidate has engaged with the question and has interesting thoughts about it is a huge plus.

FWIW I would never ask these kinds of gotcha questions. I just give simple programming problems and talk through solutions with the candidates, and then throw in complications to the questions to make them more interesting and test more areas of the candidates knowledge and problem solving abilities. Yknow, like what happens on the job every day.

Re: Steve Ballmer's incorrect binary search interview question

#124

Post by throwaway_1more »

I recently interviewed for a senior level role for a complex domain (payments), this is an area I have more than a decade of experience. The interviews went flawlessly because I know payments inside out, not just in US but in UK and most EU jurisdictions. The funny bit is that the role being senior, influencing, soft communication skills and managing conflict are even more important than the subject matter expertise and I nailed those areas as well (they threw an obnoxious senior manager that kept interrupting me as I calmly answered the questions, the follow up was that my performance was a masterclass in handling conflict). The final round was with a business person who fancied himself the defacto subject matter expert and kept throwing trivia questions about payments. His plan was to go through as much trivia as he could until he could find something to justify a no. His last question (he literally stopped as soon as he got his way after this question), the question was, have you got personal experience working on real-time payments? I do, in more than one countries (US introduced this very recently as part of fednow), he pushed me about the fednow and obviously this is so new that I only have read the specifications and evaluated a few vendors to decide whether to build or buy. He used this as justification to make a negative reommendation, claiming I don't have real-time payments experience.

Honestly, I don't want to work in an environment like that, it was a large US bank and where their biggest problems are not product innovation or focusing on customer but production failures! An area I have rescued several large companies in, apart from payments expertise and made sure I communicated this. But sometimes you get lucky and don't have to find out the hard way that this place is not pleasant.

Re: Steve Ballmer's incorrect binary search interview question

#126

Post by stickfigure »

treatmesubj wrote: post #90
HarryHirsch wrote: post #58

Earlier quoted context omitted.

Like this one: https://rachelbythebay.com/w/2011/07/27/ohreally/ Yes, that happens, and elsewhere she goes on about culture in tech.

Is the guy's response really that far off? Each router checks its table for the destination, and if it doesn't know it, queries the next upstream router, its default route, the next hop. Each router likely ultimately informs you of the hand-off via a packet of some sort, and your then traceroute sends a ping/ICMP to each hop to learn how far away they are. He maybe could've been pushed to expand on what he did know i…

The stepwise increasing TTL is the fundamental mechanism that makes traceroute work. Any answer that omits this is so vacuously incomplete that it might as well be considered wrong.

Re: Steve Ballmer's incorrect binary search interview question

#127

Post by netmare »

tantalor wrote: post #57
krisoft wrote: post #54

It is also unclear if one has to keep playing. The expected value is very different if after the fifth guess one can thank Balmer for the opportunity and walk away.

Good one! Reminds me of the viral video, goes something like "I'll pay you $20 if I can pour 2 cups of water on your head" and then only pour 1 cup and walk away.

IANAL, but they either have to honor the verbal contract (pour an additional cup AND pay $20) OR the contract is void and therefore they can be sued for assault. Of course, the "can" in "if I can" may be construed as "being able to", but that's up to the jury I guess.

Re: Steve Ballmer's incorrect binary search interview question

#128

Post by AmericanChopper »

throwaway_1more wrote: post #124

I recently interviewed for a senior level role for a complex domain (payments), this is an area I have more than a decade of experience. The interviews went flawlessly because I know payments inside out, not just in US but in UK and most EU jurisdictions. The funny bit is that the role being senior, influencing, soft communication skills and managing conflict are even more important than the subject matter expertise…

That SME guy sounds like an asshole, but I used to have an interview technique where I’d ask increasingly specific and low level questions about the candidates area of expertise until it got to the point where I’d be pretty confident they wouldn’t know the answer off the top of their head. I wasn’t adversarial or rude about it, I just wanted to find out if they were comfortable saying “I don’t know”, because not knowing something is an everyday part of technical work, but not being comfortable saying it can be big source of issues.

The candidates who were otherwise the most competent tended to be the most comfortable with the I don’t know answer. Getting defensive about it I always considered to be a red flag.

Re: Steve Ballmer's incorrect binary search interview question

#129

Post by jb3689 »

mrgoldenbrown wrote: post #42
kibwen wrote: post #10

The article implies that the interviewee assumes that the number is being chosen randomly, when Ballmer could actually be choosing adversarially. However, if the interviewee assumes that Ballmer is being adversarial, then you can pick a different value as your initial guess, which causes the probabilities to shift. Even the OP assumes that the interviewee will start guessing with 50, but, because of the way binary se…

It would not be shocking to find out a cocky interviewer posed a brainteaser while leaving out a fundamental assumption, then judged an answer as incorrect because it violated that unspoken assumption - I can imagine Ballmer saying "no actually, you have to start with a guess of 50, everyone knows that."

Ah, the B type developer. Knows enough to find exciting and interesting problems but doesn’t know how to distinctly separate a type C (who can’t solve the problem at all) from a type A ( who knows the problem in and out and knows “it depends”). Not all that different to me from midlevel dev who learns about concurrency/metaprogramming/etc and starts using it as a tool for everything. Just enough to be dangerous.

Re: Steve Ballmer's incorrect binary search interview question

#130

Post by rocketbop »

AmericanChopper wrote: post #128
throwaway_1more wrote: post #124

I recently interviewed for a senior level role for a complex domain (payments), this is an area I have more than a decade of experience. The interviews went flawlessly because I know payments inside out, not just in US but in UK and most EU jurisdictions. The funny bit is that the role being senior, influencing, soft communication skills and managing conflict are even more important than the subject matter expertise…

That SME guy sounds like an asshole, but I used to have an interview technique where I’d ask increasingly specific and low level questions about the candidates area of expertise until it got to the point where I’d be pretty confident they wouldn’t know the answer off the top of their head. I wasn’t adversarial or rude about it, I just wanted to find out if they were comfortable saying “I don’t know”, because not know…

I always say I don’t know in interviews when I really don’t, rather than try to bluff. Some interviewers don’t like this though. As with the parent, perhaps that’s actually a good thing as you avoid having to work in a bad environment. Other times though, you may be being interviewed with a bad egg who you’ll never actually need to work with in the actual job.
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