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Show HN: I send out a weekly CS topic overview and code interview question

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Re: Show HN: I send out a weekly CS topic overview and code interview question

#31

Post by mgkimsal »

nevster wrote: post #30
robomartin wrote: post #26

I hate code-writing puzzles during interviews. I don't use them at all. Why? Precisely because of methods such as this one where someone might memorize or learn a bunch of patterns to common puzzles going around. They come in and ace the interview test. Does it really tell you anything about the person other than they can train themselves like an intelligent monkey to produce the correct output given an input? My pre…

We get our interviewees to sit in front of an IDE of their choice and write some simple code. And I mean simple! No fancy algorithms or tricks. I ask them to write a method that takes a list of Strings and returns a single String which is all those Strings concatenated together with spaces in-between. And oh my word, how people fail. It's truly frightening.

you're looking for something like

return myList.join(" ")

or

return implode(" ", $myList);

or something similar?

Or maybe even

$string = ''; foreach($myList as $item) { $string .= $item." "; } return trim($string);

Or something more complex? I can't really imagine it being more complex, but I can imagine people failing. I too am sometimes shocked at how people end up getting programming jobs who don't grok extremely basic concepts.

I do understand how some people end up in programming roles - often just because they show some ability to get stuff done - they're the least bad in an org, and no one else wants to do it. But that's different that someone intentionally applying for a job as a "developer" and not understanding the concept of a loop (I've met a couple over the past 15+ years in the world of paid developers).

Re: Show HN: I send out a weekly CS topic overview and code interview question

#32

Post by robomartin »

nevster wrote: post #30
robomartin wrote: post #26

I hate code-writing puzzles during interviews. I don't use them at all. Why? Precisely because of methods such as this one where someone might memorize or learn a bunch of patterns to common puzzles going around. They come in and ace the interview test. Does it really tell you anything about the person other than they can train themselves like an intelligent monkey to produce the correct output given an input? My pre…

We get our interviewees to sit in front of an IDE of their choice and write some simple code. And I mean simple! No fancy algorithms or tricks. I ask them to write a method that takes a list of Strings and returns a single String which is all those Strings concatenated together with spaces in-between. And oh my word, how people fail. It's truly frightening.

This is interesting. I'd like to know more. Are you targeting young inexperienced programmers? Are they just out of school? What kind of filtering do you have prior to bringing them in?

I have never hired a recent grad for programming.

I used to own an electronics manufacturing company near UC Riverside (California) some time back. We had pick-and-place machines and the usual assortment of equipment you'd have for the assembly and testing of circuit boards. We made microprocessor-driven industrial motor controls.

During that time I thought it'd be great to hire engineering students. As someone who was a capable electronics hobbyist before I even touched college I assumed that these kids would be hell-bent to work in electronics as I was when I was in college. Not so. I probably went through 15 or 20 of them before I found a couple that were worth the effort.

When it came to programming I never hired anyone with anything less than five years of demonstrable experience.

Re: Show HN: I send out a weekly CS topic overview and code interview question

#33

Post by nevster »

robomartin wrote: post #32
nevster wrote: post #30

Earlier quoted context omitted.

We get our interviewees to sit in front of an IDE of their choice and write some simple code. And I mean simple! No fancy algorithms or tricks. I ask them to write a method that takes a list of Strings and returns a single String which is all those Strings concatenated together with spaces in-between. And oh my word, how people fail. It's truly frightening.

This is interesting. I'd like to know more. Are you targeting young inexperienced programmers? Are they just out of school? What kind of filtering do you have prior to bringing them in? I have never hired a recent grad for programming. I used to own an electronics manufacturing company near UC Riverside (California) some time back. We had pick-and-place machines and the usual assortment of equipment you'd have for th…

We were looking for experienced Senior Java Developers. I'm talking about people who have 10 or more years of experience on their CV, working for well known companies - large banks etc. We give the CVs a fairly good going over before deciding to get someone in. They've also responded to a short questionnaire about their experience with agile methodologies. (And of course, the job agencies have supposedly already done some sort of filtering.)

Interview nerves are one thing but even if you're nervous you should still be able to do the equivalent of multiplying 5 * 10.

Re: Show HN: I send out a weekly CS topic overview and code interview question

#34

Post by nevster »

mgkimsal wrote: post #31
nevster wrote: post #30

Earlier quoted context omitted.

We get our interviewees to sit in front of an IDE of their choice and write some simple code. And I mean simple! No fancy algorithms or tricks. I ask them to write a method that takes a list of Strings and returns a single String which is all those Strings concatenated together with spaces in-between. And oh my word, how people fail. It's truly frightening.

you're looking for something like return myList.join(" ") or return implode(" ", $myList); or something similar? Or maybe even $string = ''; foreach($myList as $item) { $string .= $item." "; } return trim($string); Or something more complex? I can't really imagine it being more complex, but I can imagine people failing. I too am sometimes shocked at how people end up getting programming jobs who don't grok extremely…

Yes, something like that.

We were interviewing for Java devs so basically a method with this signature:

public static String concatenate(List strings)

And I have a StringUtils class ready to go with an example method and say "imagine there are a bunch of methods in this class and we want production ready code"

There's a lot you can learn.

- do they decide to write unit tests up front (note that our questionnaire asks about their testing experience and everyone rhapsodizes about their strong testing background)

- if not, once they've written the method, how do they respond to the question "How do we know if it works?" (cue people writing main methods within the StringUtils class)

- what kind of unit tests do they write? Can they come up with good tests that cover all cases

- what names do they give to their methods/parameters/variables. (One guy called his method bangThemTogether)

- what bugs do they have - what cases do they miss

- if a unit test fails how do they go about fixing it (interestingly only 2 people fired up the debugger)

- do they ask questions if they need clarification

Minor things

- keyboard/IDE skills - do they laboriously type everything or have they taken the time to learn their preferred tool

- can they explain what they're doing - do they speak at all...

There's a second part to the practical - a bit of a code review/refactoring exercise. Sometimes I skip it because they've taken more than 30 minutes on the first part or their just so bad it's not worth continuing.

BTW we've interviewed about 30 people with this technique. They first meet with the dev manager for culture fit and general knowledge of dev processes. Then they meet with a tech lead for a more technical interview - explain your last project etc. Then I do the practical. Many people get through the first two just fine but fail badly on the practical.

Re: Show HN: I send out a weekly CS topic overview and code interview question

#35

Post by mgkimsal »

nevster wrote: post #34
mgkimsal wrote: post #31

Earlier quoted context omitted.

you're looking for something like return myList.join(" ") or return implode(" ", $myList); or something similar? Or maybe even $string = ''; foreach($myList as $item) { $string .= $item." "; } return trim($string); Or something more complex? I can't really imagine it being more complex, but I can imagine people failing. I too am sometimes shocked at how people end up getting programming jobs who don't grok extremely…

Yes, something like that. We were interviewing for Java devs so basically a method with this signature: public static String concatenate(List strings) And I have a StringUtils class ready to go with an example method and say "imagine there are a bunch of methods in this class and we want production ready code" There's a lot you can learn. - do they decide to write unit tests up front (note that our questionnaire asks…

Good list of how you interview/test and what your expectations are! I'd have to admit, I don't often even consider writing a test for a method that would just return a join() - I trust the join() method in the underlying language 'just works', although there are other reasons for writing tests (error handling, etc).

I do some PHP teaching, and one thing I got some good feedback from was giving students assignments that had asserts in them. Not quite unit-testing specifically (not using a full testing harness), but I'd give them some shell code with assert statements and they'd need to 'make it work'.

The sharp ones actually made it work, and gave me feedback that they appreciated that a lot, as it showed them how to think about breaking down things in to testable parts (even trivial stuff). The not-so-sharp ones... easier to spot when they'd give me back code that obviously was never even run in the first place.

Re: Show HN: I send out a weekly CS topic overview and code interview question

#36

Post by Jagat »

nirvanatikku wrote: post #25
Jagat wrote: post #24

Earlier quoted context omitted.

Except for Gayle Laakman's extensive marketing and the heavy user base that followed, I don't see why careercup is popular in the first place. It is a terrible website with ads for her two books taking up half of the home page space. It would be great if someone could start a stackexchange site for discussing CS interview questions; I'm pretty sure the quality of questions and discussions would be better then.

um.. I think it's popular because it essentially is like a stackexchange for CS interview questions..... it has a ton of questions, some of which _actually_ popped up during interviews. As for the ads, I had no trouble ignoring them.

"it essentially is like a stackexchange for CS interview questions"

except for the bad website and tons of ads.

Re: Show HN: I send out a weekly CS topic overview and code interview question

#37

Post by robomartin »

nevster wrote: post #33
robomartin wrote: post #32

Earlier quoted context omitted.

This is interesting. I'd like to know more. Are you targeting young inexperienced programmers? Are they just out of school? What kind of filtering do you have prior to bringing them in? I have never hired a recent grad for programming. I used to own an electronics manufacturing company near UC Riverside (California) some time back. We had pick-and-place machines and the usual assortment of equipment you'd have for th…

We were looking for experienced Senior Java Developers. I'm talking about people who have 10 or more years of experience on their CV, working for well known companies - large banks etc. We give the CVs a fairly good going over before deciding to get someone in. They've also responded to a short questionnaire about their experience with agile methodologies. (And of course, the job agencies have supposedly already done…

I am speechless. Don't know what to say.

Re: Show HN: I send out a weekly CS topic overview and code interview question

#38

Post by theyak »

nevster wrote: post #30
robomartin wrote: post #26

I hate code-writing puzzles during interviews. I don't use them at all. Why? Precisely because of methods such as this one where someone might memorize or learn a bunch of patterns to common puzzles going around. They come in and ace the interview test. Does it really tell you anything about the person other than they can train themselves like an intelligent monkey to produce the correct output given an input? My pre…

We get our interviewees to sit in front of an IDE of their choice and write some simple code. And I mean simple! No fancy algorithms or tricks. I ask them to write a method that takes a list of Strings and returns a single String which is all those Strings concatenated together with spaces in-between. And oh my word, how people fail. It's truly frightening.

Reading your description below (test cases et. al.), it doesn't seem as simple as you first make it seem. I start with something like, "Write a loop that displays the numbers 1 to 100." About 80% of the people I phone interview fail this test. Almost 100% of newly graduated students fail. I'm not sure if they are overthinking it, if schools are no longer teaching anything practical, or what.

Re: Show HN: I send out a weekly CS topic overview and code interview question

#39

Post by nevster »

robomartin wrote: post #37
nevster wrote: post #33

Earlier quoted context omitted.

We were looking for experienced Senior Java Developers. I'm talking about people who have 10 or more years of experience on their CV, working for well known companies - large banks etc. We give the CVs a fairly good going over before deciding to get someone in. They've also responded to a short questionnaire about their experience with agile methodologies. (And of course, the job agencies have supposedly already done…

I am speechless. Don't know what to say.

Just for some clarification, when I say fail, I really mean fail to do it well.

Most of them at least manage to get it working but don't necessarily cover all the problems that can arise and can get it to 100%, with some prompting.

It's a real joy when someone comes in who obviously loves programming. Like night and day.

Re: Show HN: I send out a weekly CS topic overview and code interview question

#40

Post by Androsynth »

nevster wrote: post #34
mgkimsal wrote: post #31

Earlier quoted context omitted.

you're looking for something like return myList.join(" ") or return implode(" ", $myList); or something similar? Or maybe even $string = ''; foreach($myList as $item) { $string .= $item." "; } return trim($string); Or something more complex? I can't really imagine it being more complex, but I can imagine people failing. I too am sometimes shocked at how people end up getting programming jobs who don't grok extremely…

Yes, something like that. We were interviewing for Java devs so basically a method with this signature: public static String concatenate(List strings) And I have a StringUtils class ready to go with an example method and say "imagine there are a bunch of methods in this class and we want production ready code" There's a lot you can learn. - do they decide to write unit tests up front (note that our questionnaire asks…

You are setting yourself up for failure using these methods.

- You're being misleading by asking them to write a concat method when you really want unit tests for that method. Just be straightforward. You're being too clever for your own good.

- People rarely code in a linear fashion. For example, I often write the meat of my methods first. Then do edge cases / error handling in a second or third pass. I have been dinged for this in interviews before. But imo, it says nothing about me as a programmer.

- You want them to be comfortable with tools, but they are behind enemy lines and under enemy fire. Dont expect them to achieve any kind of comfort level (and I would put 'thinking to use debugger' up there as something you would forget/ignore while being uncomfortable).

- When you are in extreme concentration mode, do you talk to others? Probably not. If you want them to talk, ask them questions. Again you're expecting them to read your mind. (also, keep them away from a keyboard if you want them to talk. Put them in front of a white board instead)

As others have said, talking to people and getting to know them and how they solve problems is much better than giving them mechanical interviews.

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