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This is one of my favourite tweets: https://twitter.com/mxcl/status/608682016205344768 https://twitter.com/mxcl/status/608682016205344768 I've seen some rather

This is one of my favourite tweets: https://twitter.com/mxcl/status/608682016205344768 https://twitter.com/mxcl/status/608682016205344768 I've seen some rather complex problems being asked in interviews. I've always wondered why my credentials don't seem to matter when it comes to programming skills. I have a masters degree where i did some very tricky algorithms and I even open-sourced it for all to see. But every time I've been looking for a job, i have to rehearse some leetcode problems so that i can put on a good show for 45 minutes. I get that deep-dives matter a lot and i can respect some of those exercises. These are crucial for senior positions since ideas are more important than code. Then I really get the life story kind of interviews because relating to coworkers and culture fit are hugely important. It's just the dang leetcode that ticks us all off isn't it?

vultour 5y ago
I was also a fan of this tweet until I found out what inverting a binary tree actually is. Being asked to code relatively complicated algorithms like balancing a binary tree is one thing, but this guy essentially failed FizzBuzz. At that point it’s not about testing the limits of your candidate but filtering out the low hanging fruit. Obviously I don’t have the whole story of the interview, but it makes me a little worried for homebrew.
- SQueeeeeL 5y ago
  Inverting a binary tree is essentially trivia in the context of most programming, honestly, if I had to do it without a library I'd be extremely worried I'd fuck it up in some subtle way. Max Howell obviously has a strong understanding of file systems, web protocols, package management, and a whole other suite of skills I'm too stupid to understand.
- pydry 5y ago
  The fact it was trivia irrelevant to most programmers is precisely why it was such a brain dead question. Asking what FizzBuzz is is similarly useless and would also make an abysmal question.
- ClumsyPilot 5y ago
  "until I found out what inverting a binary tree actually is" So do you consider youself a terrible, unhire-able developer? Presumable your still has quadrupled since you found out this information?
  - vultour 5y ago
    No, but I assume that the inteviewer will elaborate if you ask them what they mean. I don't consider people who don't know what FizzBuzz is terrible developers, not knowing how to implement it after an explanation is a red flag though.
- jerf 5y ago
  No, it's not FizzBuzz. It's a recursive algorithm, which FizzBuzz isn't. (Or doesn't have to be. Let's not cite crazy repos with dozens of solutions deliberately obfuscated.) That automatically takes it out of FizzBuzz range. If you're a functional programmer, it's probably something you can just bang out. I've done functional programming. But it's been a while. In an interview situation, I'd definitely need some time to struggle through it. What gives? I claim to be a senior developer of ~25 years experience? Why can't I just bang out the roughly ten-line solution it would be in Haskell, including the requisite data declarations? Well, in my 25 years of experience, yes, I've covered everything that is necessary to do that problem, but I've got to drag it out of storage and rehydrate it manually, because I don't do this sort of thing every day lately. Or ever, really, because what senior dev is running around implementing Computer Science 301 data structures every day anymore? Pretty much just one currently implementing a brand new language that needs those basic structures in its standard library. I'd get there. It wouldn't even necessarily take long. But I can understand why an interviewer asking this question ten times a week who knows the answer forward and backward might find taking even 5 minutes to be an unimpressive performance for something that such an expert should clearly just be able to scribble down in one shot, right? And I'm gonna be honest. If you ask me to balance a possibly-unbalanced sorted binary tree, I'm basically going to be re-deriving the answer from scratch. Yeah, I covered it. Probably even did a homework assignment on it in C. But my job for the past 25 years has not been implementing balanced binary trees.
SQueeeeeL 5y ago
People cheat their way through credentials all the time, having a masters degree doesn't tell you anything about a person except they maybe sat in a room on their phone while someone discussed the nuances of Church's Thesis. And most interviewers aren't valued enough by a company to really give a shit who you are, there is just too much happening and too many interviews, so they just can't be asked to look at your Github. The game and well are poisoned at many levels. There's just too much money on the table at most modern tech companies to trust anything.
- cogman10 5y ago
  Bingo. I do quite a few coding interviews for my company and, frankly, the pass rate on the coding interview is dismal. It's one of our most effective filters for bad candidates. What sort of torturous questions do I ask? Merge 2 sorted arrays is one of my favorite. How many people can pass that? less than 50%. A good number of people don't even get to the "concat the 2 arrays into 1 array and sort" sort of solution. It's really that bad. These are people with "15 years of software development experience" failing really basic coding problems. I really wish I didn't have to ask that sort of question, but at the same time, I don't want to work with anyone that can't solve it (even "under pressure"). The fact is, a lot of programmers will go off the deep end with simple problems. This joke[1] still relatively accurately describes the mentality of a bunch of programmers in the industry. [1] http://4.bp.blogspot.com/-Hk1mt-RKYLc/UOkxShm6NrI/AAAAAAAACqo/LVmqHOfWV7g/s1600/20091116-so-large.gif http://4.bp.blogspot.com/-Hk1mt-RKYLc/UOkxShm6NrI/AAAAAAAACq...
  - JoeAltmaier 5y ago
    I got to wonder, are all those people really incompetent? See, another take is that they all clutch when being interviewed. And maybe not every interview; maybe it matters how the interviewer approaches it. It's not 'under pressure'. Real pressure is schedules and deployments and compute constraints. Not somebody looking over their shoulder.
    - cogman10 5y ago
UncleMeat 5y ago
Notably, he was never asked to invert a binary tree and I don't believe he ever got confirmation about why he was rejected. Given how he responded, I wouldn't be stunned if the answer was not his technical performance.
- dahart 5y ago
  I have definitely been part of interview processes where the team unanimously rejected experienced candidates who express visceral negative and incredulous reactions to being asked to demonstrate basic programming proficiency. The story here has hints that it may be in this category. Some candidates with decades of experience expect to immediately have philosophical discussion about where software is headed, and offered their choice of management/architect positions without talking about code, and get upset when the interview starts out with some softballs. The irony is they get ejected before the interview gets to the good stuff, we do ask about philosophy and management, but a bad attitude can take that off the table very quickly.
  - rimliu 5y ago
    Oh, I am sure they are happier that way. Bad attitude goes both ways.
    - dahart 5y ago
      I'm not sure I understand your zinger. Are you saying that it's unreasonable to ask experienced programmers to demonstrate a small amount of their programming ability, or to ask basic or easy questions?
fingerlocks 5y ago
We don't know the full story behind that tweet. Inverting a binary tree is not exactly a difficult problem. They could have even spoon fed the author with "Ok, here's the code to traverse a binary tree. This is what it means to invert a subtree. How would you invert the rest of the tree?"
marcinzm 5y ago
I've had plenty of candidates with great credentials who utterly bombed relatively simple coding problems. Not fizz-buzz but also not that much more difficult.

vultour 5y ago

I was also a fan of this tweet until I found out what inverting a binary tree actually is. Being asked to code relatively complicated algorithms like balancing a binary tree is one thing, but this guy essentially failed FizzBuzz. At that point it’s not about testing the limits of your candidate but filtering out the low hanging fruit. Obviously I don’t have the whole story of the interview, but it makes me a little worried for homebrew.

SQueeeeeL 5y ago
Inverting a binary tree is essentially trivia in the context of most programming, honestly, if I had to do it without a library I'd be extremely worried I'd fuck it up in some subtle way. Max Howell obviously has a strong understanding of file systems, web protocols, package management, and a whole other suite of skills I'm too stupid to understand.
pydry 5y ago
The fact it was trivia irrelevant to most programmers is precisely why it was such a brain dead question. Asking what FizzBuzz is is similarly useless and would also make an abysmal question.
ClumsyPilot 5y ago
"until I found out what inverting a binary tree actually is" So do you consider youself a terrible, unhire-able developer? Presumable your still has quadrupled since you found out this information?
- vultour 5y ago
  No, but I assume that the inteviewer will elaborate if you ask them what they mean. I don't consider people who don't know what FizzBuzz is terrible developers, not knowing how to implement it after an explanation is a red flag though.
jerf 5y ago
No, it's not FizzBuzz. It's a recursive algorithm, which FizzBuzz isn't. (Or doesn't have to be. Let's not cite crazy repos with dozens of solutions deliberately obfuscated.) That automatically takes it out of FizzBuzz range. If you're a functional programmer, it's probably something you can just bang out. I've done functional programming. But it's been a while. In an interview situation, I'd definitely need some time to struggle through it. What gives? I claim to be a senior developer of ~25 years experience? Why can't I just bang out the roughly ten-line solution it would be in Haskell, including the requisite data declarations? Well, in my 25 years of experience, yes, I've covered everything that is necessary to do that problem, but I've got to drag it out of storage and rehydrate it manually, because I don't do this sort of thing every day lately. Or ever, really, because what senior dev is running around implementing Computer Science 301 data structures every day anymore? Pretty much just one currently implementing a brand new language that needs those basic structures in its standard library. I'd get there. It wouldn't even necessarily take long. But I can understand why an interviewer asking this question ten times a week who knows the answer forward and backward might find taking even 5 minutes to be an unimpressive performance for something that such an expert should clearly just be able to scribble down in one shot, right? And I'm gonna be honest. If you ask me to balance a possibly-unbalanced sorted binary tree, I'm basically going to be re-deriving the answer from scratch. Yeah, I covered it. Probably even did a homework assignment on it in C. But my job for the past 25 years has not been implementing balanced binary trees.

SQueeeeeL 5y ago

People cheat their way through credentials all the time, having a masters degree doesn't tell you anything about a person except they maybe sat in a room on their phone while someone discussed the nuances of Church's Thesis. And most interviewers aren't valued enough by a company to really give a shit who you are, there is just too much happening and too many interviews, so they just can't be asked to look at your Github. The game and well are poisoned at many levels. There's just too much money on the table at most modern tech companies to trust anything.

cogman10 5y ago
Bingo. I do quite a few coding interviews for my company and, frankly, the pass rate on the coding interview is dismal. It's one of our most effective filters for bad candidates. What sort of torturous questions do I ask? Merge 2 sorted arrays is one of my favorite. How many people can pass that? less than 50%. A good number of people don't even get to the "concat the 2 arrays into 1 array and sort" sort of solution. It's really that bad. These are people with "15 years of software development experience" failing really basic coding problems. I really wish I didn't have to ask that sort of question, but at the same time, I don't want to work with anyone that can't solve it (even "under pressure"). The fact is, a lot of programmers will go off the deep end with simple problems. This joke[1] still relatively accurately describes the mentality of a bunch of programmers in the industry. [1] http://4.bp.blogspot.com/-Hk1mt-RKYLc/UOkxShm6NrI/AAAAAAAACqo/LVmqHOfWV7g/s1600/20091116-so-large.gif http://4.bp.blogspot.com/-Hk1mt-RKYLc/UOkxShm6NrI/AAAAAAAACq...
- JoeAltmaier 5y ago
  I got to wonder, are all those people really incompetent? See, another take is that they all clutch when being interviewed. And maybe not every interview; maybe it matters how the interviewer approaches it. It's not 'under pressure'. Real pressure is schedules and deployments and compute constraints. Not somebody looking over their shoulder.
  - cogman10 5y ago

UncleMeat 5y ago

Notably, he was never asked to invert a binary tree and I don't believe he ever got confirmation about why he was rejected. Given how he responded, I wouldn't be stunned if the answer was not his technical performance.

dahart 5y ago
I have definitely been part of interview processes where the team unanimously rejected experienced candidates who express visceral negative and incredulous reactions to being asked to demonstrate basic programming proficiency. The story here has hints that it may be in this category. Some candidates with decades of experience expect to immediately have philosophical discussion about where software is headed, and offered their choice of management/architect positions without talking about code, and get upset when the interview starts out with some softballs. The irony is they get ejected before the interview gets to the good stuff, we do ask about philosophy and management, but a bad attitude can take that off the table very quickly.
- rimliu 5y ago
  Oh, I am sure they are happier that way. Bad attitude goes both ways.
  - dahart 5y ago
    I'm not sure I understand your zinger. Are you saying that it's unreasonable to ask experienced programmers to demonstrate a small amount of their programming ability, or to ask basic or easy questions?

fingerlocks 5y ago

We don't know the full story behind that tweet. Inverting a binary tree is not exactly a difficult problem. They could have even spoon fed the author with "Ok, here's the code to traverse a binary tree. This is what it means to invert a subtree. How would you invert the rest of the tree?"

marcinzm 5y ago

I've had plenty of candidates with great credentials who utterly bombed relatively simple coding problems. Not fizz-buzz but also not that much more difficult.