Steve Ballmer's incorrect binary search interview question • Hacker News Board

Re: Steve Ballmer's incorrect binary search interview question

#91

Post by krisoft » Tue, Sep 03, 2024, 4:01 PM UTC

mupuff1234 wrote: post #66

dannyw wrote: post #32

Earlier quoted context omitted.

“As a SWE, I seek to understand important context first, before jumping to build or code. First, I’d like to ask if you’ll guess randomly and fairly, or adversarially?” “Secondly, when significant money is involved, I make sure to verify any inputs. I’m considering the situation, not you personally, untrusted. How can I verify it, or do you want me to proceed assuming that’s verified?” Those are great questions, but…

"as you, my interviewer, are a capable SWE I assume you gave me all the context needed to solve the problem". The interviewing game of asking clarification questions is silly and should stop. In the system design portion I can understand it, but not when asked a direct technical question. It's perfectly fine to ask followup questions with added constraints or just directly say that the specification is fuzzy and need…

> but not when asked a direct technical question.

This is anything but a direct technical question though.

> It's perfectly fine to ask followup questions with added constraints, but having the guessing game to figure out those constraints is nonsense.

You say that. I say people being able to ask the right question is one of the most important skills to be a productive developer. So of course as an interviewer I want to know if they can do it.

I don't know how it works where you are, but we don't have a big book of perfectly defined specifications for our work. I guess if we could get one of those that would improve our productivity. But until we obtain one we will keep testing candidates on their ability to ask questions.

Re: Steve Ballmer's incorrect binary search interview question

#92

Post by jncfhnb » Tue, Sep 03, 2024, 4:03 PM UTC

enneff wrote: post #48

mrgoldenbrown wrote: post #42

Earlier quoted context omitted.

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."

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.

> I see you passed this guy after a single guess. Why was that?

> Well, he guessed 69, sir, so I assumed he was doing some serious game theoretic calculations

Re: Steve Ballmer's incorrect binary search interview question

#93

Post by eterevsky » Tue, Sep 03, 2024, 4:03 PM UTC

This is a game with imperfect information, and the optimal strategy for each player is probably different from "pick any number at random" and "run off-the shelf binary search".

Re: Steve Ballmer's incorrect binary search interview question

#94

Post by krisoft » Tue, Sep 03, 2024, 4:04 PM UTC

enneff wrote: post #48

mrgoldenbrown wrote: post #42

Earlier quoted context omitted.

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."

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.

Not really. The question was "Should you accept to play this game?" That is not a question where a number is an expected answer.

Re: Steve Ballmer's incorrect binary search interview question

#95

Post by cranium » Tue, Sep 03, 2024, 4:04 PM UTC

justusthane wrote: post #59

Is there a name for the fallacy where you attribute your success in life to your own intelligence, and thus assume that you are smarter than everyone else, and that you therefor must be right about everything? Sort of an opposite impostor syndrome?

The "fundamental attribution error" is a bias where people attribute their own success to their inner abilities and other people success to external circumstances. (It's the reverse when thinking about failure)

For the second part of "I'm superior and know-it-all", I'd say it's good ol' jerk-ery?

Re: Steve Ballmer's incorrect binary search interview question

#96

Post by JackFr » Tue, Sep 03, 2024, 4:09 PM UTC

dllthomas wrote: post #86

NickC25 wrote: post #76

Earlier quoted context omitted.

One of the worst interviews I ever had was just like that. Often times, the "gotcha" part is just dumb and nonsensical, yet gives the interviewer(s) a sense of misguided (false) superiority, and wastes everyone's time. I would venture to say that 99% of the time it's complete un-indicative of how effective the candidate would be in the role. Referring to my aforementioned bad interview - the question, after all the t…

> How on earth does that indicate if a junior frontend dev can do their job or not? Playing devil's advocate, maybe a junior frontend dev that doesn't trust that they understand what someone is asking for and pushes back on bits that should be obvious will perform better (in some contexts?) than one that doesn't. For a junior role in particular, though, it really doesn't seem like that should be the threshold and it…

Might be good as an exercise in a workshop on requirements gathering, as part of an interview absolutely stupid.

Re: Steve Ballmer's incorrect binary search interview question

#97

Post by hi-v-rocknroll » Tue, Sep 03, 2024, 4:12 PM UTC

__coaxialcabal wrote: post #36

Eumenes wrote: post #2

Didn't Steve Ballmer start off at MSFT essentially in a biz ops role, supporting execs when the company was super small? Interesting how he became technical as the company grew. Pretty rare.

It's surprising the extent to which the tech community overfits towards classifying intelligent individuals as either exclusively technical or nontechnical. Recruiters are especially weak in this regard, e.g., if you've ever been effective at sales or people leadership, you are likely ineffective at swe or data science or vice versa. The most intelligent folks I've worked with are very diverse in their interests and…

Yep. Pigeonholing by narrow thinking individuals who aren't accustomed to ambiguity or lateral thinking, especially when exhibit talents in more than just technical areas, a person becomes "nontechnical" to a nonzero proportion of technical people while remaining "too technical" for a large fraction of business people.

PS: Recruiters generally come from the same cloth as car sales and sports, so they're not usually going to be the sharpest pencils in the drawer.

Re: Steve Ballmer's incorrect binary search interview question

#98

Post by hi-v-rocknroll » Tue, Sep 03, 2024, 4:14 PM UTC

re-thc wrote: post #5

Eumenes wrote: post #2

Didn't Steve Ballmer start off at MSFT essentially in a biz ops role, supporting execs when the company was super small? Interesting how he became technical as the company grew. Pretty rare.

> Didn't Steve Ballmer start off at MSFT essentially in a biz ops role Yes, business manager. > Interesting how he became technical as the company grew. That's not clear from this. This shows he knew some concepts as part of managing different teams in the company.

Ballmer was good at riding coat-tails of others as a supporting figure but eventually started running MSFT into the ground. He demanded to personally evaluate every M&A activity >$10M. No bueno.

Re: Steve Ballmer's incorrect binary search interview question

#99

Post by FabHK » Tue, Sep 03, 2024, 4:15 PM UTC

michaelt wrote: post #16

toolz wrote: post #3

Title is wrong in implying Balmer is incorrect and the article shows that the title is wrong. If clickbait is misleading, then this is worse than clickbait, no? > Ballmer states that the answer is "No" for two reasons: firstly, because he can pick numbers that'll be the most difficult for you... The article goes on to show that there are numbers where a binary search always has the guesser paying $1

Also the number only exists in Ballmer's mind, so if he wanted to, he could change it to be unfavourable should you make a lucky guess. Here, you can play the game with me. Higher. Lower. Higher. Higher. Lower. Correct. Six guesses, you owe me $1.

0$, as posed.

Re: Steve Ballmer's incorrect binary search interview question

#100

Post by layer8 » Tue, Sep 03, 2024, 4:15 PM UTC

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…

If Ballmer is being adversarial, he won’t pick the number at the start, and always win.

Of course you can set up the game such that Ballmer has to commit on a number at the start of the game (by sealing it in an envelope or whatever), but that wasn’t specified.