In interviews and in general, it usually is a good idea to get a correct yet inefficient solution and then try to optimize it. This usually yields better insights in my experience. Here is a quadratic solution:
I failed a Twitter interview
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Re: I failed a Twitter interview
#72This question involves an "a-ha" moment (for the linear-time solution) and was thus banned from interviews at Google last year. Don't use questions involving eureka moments. They reveal nothing about the candidate. Edit: It should be noted that this question was used for a long time at Google, Microsoft, and many other places. It's a terrible question.
the word you are looking for is insight problem. Insight problems are problems in which people unable accurately predict their progress. As in if you asked someone to continually report their progress on a problem as they attempted to solve it they would say something like, "0% 0% 0% oh I'finished". Insight problem solving is a topic of significant interest in cognitive science right now and most recently it was found that applying a small amount of electric current to the right side of the brain greatly increase our capacity for insight problem solving. It is pretty dope.
Re: I failed a Twitter interview
#73Algorithmic interview questions should ideally have multiple solutions of varying complexity. The "brute force" solution should be obvious to anyone competent enough. If they are able to code it up with reasonable clarity and test cases, that is a good start (think of it as the fizzbuzz level). Good candidates should be able to get to the "ideal/aha" solution with some hints. In fact, that process reveals a lot about the candidate. If the candidate doesn't "get" to the ideal solution on their own, it shouldn't be held against them IMO.
Re: I failed a Twitter interview
#74This question involves an "a-ha" moment (for the linear-time solution) and was thus banned from interviews at Google last year. Don't use questions involving eureka moments. They reveal nothing about the candidate. Edit: It should be noted that this question was used for a long time at Google, Microsoft, and many other places. It's a terrible question.
Is there a definition of ah-ha moment? Seems like what strikes one person as an "ah-ha" insight might be a baseline assumption of another person's thought process.
I think it can be summed up to; you're expecting a specific final solution. Open ended questions that don't have a best solution will require you to pay more attention to the process, rather than the result. In this article, the guy was smart enough to figure it out, but during the pressure of the interview, didn't stumble upon the right solution or fully verify his initial solution, but was able to as soon as the pressure was off. With an open ended solution it's not about getting it right, but how you try to come up with an answer.
Re: I failed a Twitter interview
#75Earlier quoted context omitted.
"this is a seriously bad way of hiring developers" We can't reasonably assume that Twitter uses this sort of question in all their developer interviews. We don't have enough data for that. Perhaps this guy was going for a role where solving problems quickly and under pressure was a key requirement. If that were the case, this is pretty much a perfect interview question.
I have hard time imagining what position, at least if we're talking about software engineering, would require solving abstract toy problems in a timeframe of less than an hour without a chance to ever go back and improve your solution. I'd say it's "did you see this problem before" kind of question. Which means Twitter probably lost a capable and smart hire because he couldn't quickly give a perfect answer to useless…
Twitter interview puzzle creator?
Re: I failed a Twitter interview
#76> The next day I showed this question to my TA, who's a PhD student in theoretical computer science. After 40 minutes he was also stuck with nothing. That just doesn't speak well of this particular PhD. The one-pass solution is rather obvious. I hate puzzle-based interviews with passion, but this is actually a very reasonable question and it does help to tell apart people with "theoretical" computer science skills fr…
Not all theoretical CS is focused on algorithms, and if this were specifically for an algorithm focused position, I would ask a more in depth and relevant question. This question might be suited for a small subset of jobs, but considering that the guy is still in school doing internships, I would assume the position was a generic software developer position, which makes this a bad question.
Re: I failed a Twitter interview
#77I think this is a terrible way to conduct a phone interview. I think about code visually, and this is a very visual question, so thinking about this entirely in my head is way harder than writing it down. I'd be worried that having a computer in front of me would give the wrong impression, if typing sounds are heard on the phone, and I wouldn't want to discount a potential great developer just because they were too nervous to ask if it were ok to grab a pen and paper. With all the ways we can communicate now, it seems archaic to ask someone to think through and explain their code over the phone.
Re: I failed a Twitter interview
#78This question involves an "a-ha" moment (for the linear-time solution) and was thus banned from interviews at Google last year. Don't use questions involving eureka moments. They reveal nothing about the candidate. Edit: It should be noted that this question was used for a long time at Google, Microsoft, and many other places. It's a terrible question.
the word you are looking for is insight problem. Insight problems are problems in which people unable accurately predict their progress. As in if you asked someone to continually report their progress on a problem as they attempted to solve it they would say something like, "0% 0% 0% oh I'finished". Insight problem solving is a topic of significant interest in cognitive science right now and most recently it was foun…
How much current? Do you think it would be doable to make a "thinking hat" to wear at job interviews?
Re: I failed a Twitter interview
#79> The next day I showed this question to my TA, who's a PhD student in theoretical computer science. After 40 minutes he was also stuck with nothing. That just doesn't speak well of this particular PhD. The one-pass solution is rather obvious. I hate puzzle-based interviews with passion, but this is actually a very reasonable question and it does help to tell apart people with "theoretical" computer science skills fr…
While I do not think that the problem is hard in a sense that if you came to me and wanted it solved for you I couldn't do it. I do think that it is a horrible interview question.
I fail to see why one would ask this kind of question and what one would take away from the answer.
How does being able to solve problem like this help make Jack Dorsey richer and more respected? How does it help Twitter users have a better experience? How does it help the interviewer assess whether this dude on the other side will make his life more bearable by not shitting all over the carpet?
I think it is mostly a form of geek bullying and intellectual mastrubation for its own sake. I have a message for the people running companies where these kinds of hiring practices are taking place. You have some insane geeks on the loose and you should catch them and lock them into the darkest dungeon as they __will__ ruin your company.
Re: I failed a Twitter interview
#80I think this is a terrible way to conduct a phone interview. I think about code visually, and this is a very visual question, so thinking about this entirely in my head is way harder than writing it down. I'd be worried that having a computer in front of me would give the wrong impression, if typing sounds are heard on the phone, and I wouldn't want to discount a potential great developer just because they were too n…
They generally have you code on a shared pad like collabedit. It's not over the phone for that part.