5 ms·

Steve Yegge's five essential phone-screen questions

48 points by vinutheraj 17y ago

losethos 17y ago
I had a boss who I went to lunch with and we discussed hiring. He wanted to keep things secret. "In academia, if it's good you want to publish; in industry, keep it a secret."
andrewcooke 17y ago
it's always difficult to comment on these kinds of posts because, obviously, they're pretty general, and the person doing the interview would need to use their own discretion, etc. but having said that, one of the example questions seemed a bit odd to me. the idea was to find out whether a candidate knows how to use grep or similar. and the first case is fair enough - phone numbers with a given pattern. but a later example was reformatting code so that parentheses had spaces around them. now anyone that tries reformatting code with a regular expression deserves everything they get. almost no programming languages have regular grammars, and even if they do, they are probably fiendishly complex (think of comments and strings). to make things worse, if you get something wrong you end up running the risks of introducing some kind of obscure bug in your code... as i said, maybe i am being too picky. but that was the one example that jumped out as a red flag for the author's experience (which is odd, as i recognise the name, even though i don't really follow personalities on the web much). edit: thinking some more, maybe i am being too picky. just last night i used sed to change some import statements in python code. but messing around with parens sounds like playing with fire to me. i vaguely remember, years ago, trying to enforce encoding standards with a regexp based rewriter for some obscure language that had no easily available parser. the memory is a blur, except for the pain...
- silentbicycle 17y ago
  It's a good sign if the interviewee thinks about an RE modifying the strings in a program, though. While programmers who think RE are all-powerful are likely outnumbered by those completely ignorant of them, they're out there. It's important to know REs' limitations - sometimes you need an actual parser. (My favorite example: RFC-822-compliant e-mail address validation - http://www.ex-parrot.com/~pdw/Mail-RFC822-Address.html http://www.ex-parrot.com/~pdw/Mail-RFC822-Address.html)
RiderOfGiraffes 17y ago
An old favorite ... http://searchyc.com/five+phone+screen http://searchyc.com/five+phone+screen http://news.ycombinator.com/item?id=94990 http://news.ycombinator.com/item?id=94990 http://news.ycombinator.com/item?id=941925 http://news.ycombinator.com/item?id=941925 My wife just watched me do this search and trawl through the results, and then she asked me why. Why spend all that time cross-referencing something when the search terms are so vague you need to go through pages to find the duplicates? The answer is that sometimes I find other items of interest. I don't read HN fanatically, and sometimes items come and go without my seeing them. Occasionally, more than occasionally, one turns up in a search like this, so it's worth doing for the side effect.
- deleted 17y ago
  [deleted]
j_baker 17y ago
It should be noted that Steve has said elsewhere that he can't use these questions anymore because everyone knows them. Thus, I wouldn't follow this template too closely. That said, it's a good way to get a general idea about how to ask these kinds of questions.
- neilk 17y ago
  Those particular questions are now toast, but the essay was always about the five subjects he asks about.
- gaius 17y ago
  That's a problem for everyone. We (like many other organizations) use third party recruiters, and the latest ad one of them has put out very clearly indicates that they've been quizzing (unsuccessful) candidates about what we asked, and are now trying to coach candidates in them. Unfortunately said recruiter is non-technical and a) the ad now makes no sense (e.g. if I ask "what is a deadlock?" it doesn't translate into "must have 5 years of experience of deadlocks") and b) some of the canned answers they've been giving to our questions are wrong, so we get a stream of candidates all parroting the same wrong thing.
  - silentbicycle 17y ago
    It'd make me laugh if somebody's resume listed "5 years experience with C++, deadlocks, linking errors", though. :)
    - gaius 17y ago
      No joke, one dude I interviewed claimed so-many years experience of C++, it turned out he meant experience of running programs written in C++ on his PC (!) I really am utterly mystified why people do this. It was the first skill he listed. Did he not think an interviewer might ask him about it? And even on the offchance he blagged his way through the interviews, he's not going to be able to fake it to the machine and he'll be found out on his first day. It really shakes my faith in human nature, interviewing :-(
dondemarco 17y ago
Interesting...except, if you are going to do most of the talking how are you really going to find out more about the candidate? I think the problem isn't that you let the candidate do most of the talking. It is that you got lazy (as you admit) and didn't listen intently enough and ask probing questions. I think it is more useful to really probe and find out if someone understands something in sufficient depth and demonstrates a mastery of programming/software engineering principles than to answer high level questions in broad areas. The latter is much easier to do!
middus 17y ago
Am I the only one who thinks that his "Example 2: Write function to compute Nth fibonacci number" is a terrible resource hog? IMHO an iterative approach would be the way to go.
- RiderOfGiraffes 17y ago
  So, so many people miss the point(s) here. Firstly, in my direct, personal experience, just writing a candidate to write a program that compiles and runs gets rid of up to 90% of applicants. People here on HN are exceptional, but around 90% of recent applicants for a position I advertised couldn't write a FizzBuzz program that compiled and ran. Secondly, these are the starting points. From here you can ask what problems the program has. Yes, it's exponential in stack and runtime. You can write an iterative version that runs in constant stack and linear time. More subtle, and more probing, is how do you write a recursive version that also runs in small stack and time. These are the starting points, the initial cull. Don't assume they're the be all and end all.
  - falsestprophet 17y ago
    On paper? Or with a computer and compiler/interpreter?
    - silentbicycle 17y ago
      Writing pseudocode on paper will shift focus from correcting minor syntax errors to how well they understand concepts, which is arguably more important. It's still worth requiring them to produce at least a tiny piece of working code, though. I helped interview someone who couldn't explain the trade-offs between a couple different designs for a simple class hierarchy, even an obviously wrong one included as a canary. Then we asked him to write one out, and, after stalling and getting several hints from us, he nervously scratched out a (naive) MySQL schema. Despite what his resume claimed, his only programming experience consisted of PHP and a fairly shallow understanding of SQL.
    - RiderOfGiraffes 17y ago
wingo 17y ago
I feel good about all of these questions except the OO design one. I would rather declare types and write functions that operate on those types; granted it's the same, semantically, but if I focus on nouns personally I start coding stupid stuff.
- raganwald 17y ago
  I'm guessing that in an actual interview Yegge would be sympathetic to your point of view: http://steve-yegge.blogspot.com/2006/03/execution-in-kingdom-of-nouns.html http://steve-yegge.blogspot.com/2006/03/execution-in-kingdom... That being said, here's a question: How many people who self-identify as functional programmers could write an OO program competently? Compare and contrast to the question of how many people who self-identify as OO programmers could write a functional progam competently? Do the paradigms themselves have anything to do with the difference? Or is this strictly an issue of bias for other reasons?
  - smanek 17y ago
    I would guess that almost all functional programmers know OO programming, but very few OO programmers know functional programming. I think this is just because of pedagogic issues. Every introductory book/class introduces OO, but most undergraduate CS courses barely discuss functional programming (besides a semester on ML or Scheme, if you're particularly lucky). So, the people who go out off the beaten path to learn functional programming are a self selected subset that is particularly driven, curious, etc.
    - raganwald 17y ago
      That would be my conjecture about academia. In business, a certain kind of person learns the languages and paradigms that appear to be well-represented in monster.com job postings.
  - wingo 17y ago
    I do self-identify as a functional programmer, and when I have to write an OO solution to a problem, I often get it wrong. Less wrong when I'm working with a more common idiom (like a tree of widgets), more wrong when I'm striking out into the wild. In my personal (non-work) work, I don't do objects at all. I just don't find that stateful solutions sit right with me.
ynniv 17y ago
The sample code for reversing a string in Java reminded me of why I can't bring myself to use Java-the-language anymore. Clojure FTW!
luckydude 17y ago
Huh. Not impressed. One of my guys, who went on to be one of the ZFS guys, came from 3par. And they had the 3x3 test: Gives a shit Positive learning curve. Not an asshole. Make your candidates pass that and you're doing fine.

48 points by vinutheraj 17y ago

I had a boss who I went to lunch with and we discussed hiring. He wanted to keep things secret. "In academia, if it's good you want to publish; in industry, keep it a secret."

andrewcooke 17y ago

it's always difficult to comment on these kinds of posts because, obviously, they're pretty general, and the person doing the interview would need to use their own discretion, etc. but having said that, one of the example questions seemed a bit odd to me. the idea was to find out whether a candidate knows how to use grep or similar. and the first case is fair enough - phone numbers with a given pattern. but a later example was reformatting code so that parentheses had spaces around them. now anyone that tries reformatting code with a regular expression deserves everything they get. almost no programming languages have regular grammars, and even if they do, they are probably fiendishly complex (think of comments and strings). to make things worse, if you get something wrong you end up running the risks of introducing some kind of obscure bug in your code... as i said, maybe i am being too picky. but that was the one example that jumped out as a red flag for the author's experience (which is odd, as i recognise the name, even though i don't really follow personalities on the web much). edit: thinking some more, maybe i am being too picky. just last night i used sed to change some import statements in python code. but messing around with parens sounds like playing with fire to me. i vaguely remember, years ago, trying to enforce encoding standards with a regexp based rewriter for some obscure language that had no easily available parser. the memory is a blur, except for the pain...

silentbicycle 17y ago
It's a good sign if the interviewee thinks about an RE modifying the strings in a program, though. While programmers who think RE are all-powerful are likely outnumbered by those completely ignorant of them, they're out there. It's important to know REs' limitations - sometimes you need an actual parser. (My favorite example: RFC-822-compliant e-mail address validation - http://www.ex-parrot.com/~pdw/Mail-RFC822-Address.html http://www.ex-parrot.com/~pdw/Mail-RFC822-Address.html)

RiderOfGiraffes 17y ago

An old favorite ... http://searchyc.com/five+phone+screen http://searchyc.com/five+phone+screen http://news.ycombinator.com/item?id=94990 http://news.ycombinator.com/item?id=94990 http://news.ycombinator.com/item?id=941925 http://news.ycombinator.com/item?id=941925 My wife just watched me do this search and trawl through the results, and then she asked me why. Why spend all that time cross-referencing something when the search terms are so vague you need to go through pages to find the duplicates? The answer is that sometimes I find other items of interest. I don't read HN fanatically, and sometimes items come and go without my seeing them. Occasionally, more than occasionally, one turns up in a search like this, so it's worth doing for the side effect.

deleted 17y ago
[deleted]

j_baker 17y ago

It should be noted that Steve has said elsewhere that he can't use these questions anymore because everyone knows them. Thus, I wouldn't follow this template too closely. That said, it's a good way to get a general idea about how to ask these kinds of questions.

neilk 17y ago
Those particular questions are now toast, but the essay was always about the five subjects he asks about.
gaius 17y ago
That's a problem for everyone. We (like many other organizations) use third party recruiters, and the latest ad one of them has put out very clearly indicates that they've been quizzing (unsuccessful) candidates about what we asked, and are now trying to coach candidates in them. Unfortunately said recruiter is non-technical and a) the ad now makes no sense (e.g. if I ask "what is a deadlock?" it doesn't translate into "must have 5 years of experience of deadlocks") and b) some of the canned answers they've been giving to our questions are wrong, so we get a stream of candidates all parroting the same wrong thing.
- silentbicycle 17y ago
  It'd make me laugh if somebody's resume listed "5 years experience with C++, deadlocks, linking errors", though. :)
  - gaius 17y ago
    No joke, one dude I interviewed claimed so-many years experience of C++, it turned out he meant experience of running programs written in C++ on his PC (!) I really am utterly mystified why people do this. It was the first skill he listed. Did he not think an interviewer might ask him about it? And even on the offchance he blagged his way through the interviews, he's not going to be able to fake it to the machine and he'll be found out on his first day. It really shakes my faith in human nature, interviewing :-(

dondemarco 17y ago

Interesting...except, if you are going to do most of the talking how are you really going to find out more about the candidate? I think the problem isn't that you let the candidate do most of the talking. It is that you got lazy (as you admit) and didn't listen intently enough and ask probing questions. I think it is more useful to really probe and find out if someone understands something in sufficient depth and demonstrates a mastery of programming/software engineering principles than to answer high level questions in broad areas. The latter is much easier to do!

middus 17y ago

Am I the only one who thinks that his "Example 2: Write function to compute Nth fibonacci number" is a terrible resource hog? IMHO an iterative approach would be the way to go.

RiderOfGiraffes 17y ago
So, so many people miss the point(s) here. Firstly, in my direct, personal experience, just writing a candidate to write a program that compiles and runs gets rid of up to 90% of applicants. People here on HN are exceptional, but around 90% of recent applicants for a position I advertised couldn't write a FizzBuzz program that compiled and ran. Secondly, these are the starting points. From here you can ask what problems the program has. Yes, it's exponential in stack and runtime. You can write an iterative version that runs in constant stack and linear time. More subtle, and more probing, is how do you write a recursive version that also runs in small stack and time. These are the starting points, the initial cull. Don't assume they're the be all and end all.
- falsestprophet 17y ago
  On paper? Or with a computer and compiler/interpreter?
  - silentbicycle 17y ago
    Writing pseudocode on paper will shift focus from correcting minor syntax errors to how well they understand concepts, which is arguably more important. It's still worth requiring them to produce at least a tiny piece of working code, though. I helped interview someone who couldn't explain the trade-offs between a couple different designs for a simple class hierarchy, even an obviously wrong one included as a canary. Then we asked him to write one out, and, after stalling and getting several hints from us, he nervously scratched out a (naive) MySQL schema. Despite what his resume claimed, his only programming experience consisted of PHP and a fairly shallow understanding of SQL.
  - RiderOfGiraffes 17y ago

wingo 17y ago

I feel good about all of these questions except the OO design one. I would rather declare types and write functions that operate on those types; granted it's the same, semantically, but if I focus on nouns personally I start coding stupid stuff.

raganwald 17y ago
I'm guessing that in an actual interview Yegge would be sympathetic to your point of view: http://steve-yegge.blogspot.com/2006/03/execution-in-kingdom-of-nouns.html http://steve-yegge.blogspot.com/2006/03/execution-in-kingdom... That being said, here's a question: How many people who self-identify as functional programmers could write an OO program competently? Compare and contrast to the question of how many people who self-identify as OO programmers could write a functional progam competently? Do the paradigms themselves have anything to do with the difference? Or is this strictly an issue of bias for other reasons?
- smanek 17y ago
  I would guess that almost all functional programmers know OO programming, but very few OO programmers know functional programming. I think this is just because of pedagogic issues. Every introductory book/class introduces OO, but most undergraduate CS courses barely discuss functional programming (besides a semester on ML or Scheme, if you're particularly lucky). So, the people who go out off the beaten path to learn functional programming are a self selected subset that is particularly driven, curious, etc.
  - raganwald 17y ago
    That would be my conjecture about academia. In business, a certain kind of person learns the languages and paradigms that appear to be well-represented in monster.com job postings.
- wingo 17y ago
  I do self-identify as a functional programmer, and when I have to write an OO solution to a problem, I often get it wrong. Less wrong when I'm working with a more common idiom (like a tree of widgets), more wrong when I'm striking out into the wild. In my personal (non-work) work, I don't do objects at all. I just don't find that stateful solutions sit right with me.

ynniv 17y ago

The sample code for reversing a string in Java reminded me of why I can't bring myself to use Java-the-language anymore. Clojure FTW!

luckydude 17y ago

Huh. Not impressed. One of my guys, who went on to be one of the ZFS guys, came from 3par. And they had the 3x3 test: Gives a shit Positive learning curve. Not an asshole. Make your candidates pass that and you're doing fine.