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> 99% of my candidates can code, as in iterate over collections, write case statements, and call functions. Honestly, that's way too trivial to call "can code"

> 99% of my candidates can code, as in iterate over collections, write case statements, and call functions. Honestly, that's way too trivial to call "can code". I usually ask something less trivial, yet still extremely easy like "a function to check if a string is a palindrome" (I explain what a palindrome is) or "check if a substring exists in a given string". You wouldn't believe how many people "with 10 years experience" just lose all motor function in their hands and mouth, even without any time pressure.

haskellandchill 9y ago
The function to check palindrome will be composed of those building blocks, that's my meaning. Use those basic skills and composing them to solve a problem, such as palindrome, that's coding in the small to me. Coding in the large is project management and could be tested by a take home, but I'd rather tease it out by asking in person questions about organization, prioritization, and technology choice.
ryandrake 9y ago
Problem is: It's hard to judge the difference between someone who doesn't know what they are doing and someone who does but loses it under the extreme pressure of an interview wherein their entire future with the company is being determined by their performance on a 30 minute exercise. Throughout my career, I've been in professional situations where I was under a lot of pressure: Having to explain failures to executives, near-impossibly tight deadlines, production outages. At least I haven't had to testify in front of Congress yet. Absolutely NOTHING I've encountered in my professional day-to-day has the extreme level of pressure of a typical silicon valley job interview.
- calcifer 9y ago
  I understand and truly symphatize with stress the candidate is in, but someone who claims to be a "senior developer with 10 years experience" should be able to write that palindrome function in 30 whole minutes in any kind of stress scenario. Because if I hire that person, they'll be in charge of critical production systems and will face much harder problems in much more stressful situations and if they can't handle the palindrome question, I have very little confidence they can handle the actual job.
  - ryandrake 9y ago
    People are strange. I can totally picture someone who is an experienced senior, a hero under the pressure of a critical production outage, yet whose brain goes into a crash loop when sitting across from someone who has the power to deny them their dream job. Not claiming to be that hero, but I have personally had those moments where I came out of the interview, and as the disorienting fog of pressure lifted during my drive home I said to myself, "WTF happened to my brain in there? I know that stuff cold!" EDIT: I think I read this one from a commenter here, but it's so true: We're interviewing people to be music composers, but judging them by their ability to be performance artists.
    - calcifer 9y ago
      Fair enough. I certainly don't claim to know the best interview method ever; simply that, in my experience, starting with trivial coding questions has a higher benefit/risk ratio then other approaches.
  - monksy 9y ago
    I don't agree. They should be able to write that as a solution to resolve an issue. It should be very well understood why they're writing it. Additionally, if you want to keep going under that justification: you should also accept quick alternatives that aren't the naive approach. (i.e. bring out groovy, using bash, etc)
    - vorg 9y ago
      Even a "systems" language like Go is just as suitable for a "quick alternative" as a "scripty" language like Apache Groovy or Bash.
- warrenm 9y ago
  While I agree in the abstract ...honestly, it's not that hard to write at least pseudocode for problems like that regardless of the "stress" of an interview Is it reasonable to ask things like that? Maybe, maybe not. But as stressful as an interview is, it's still a basic problem (I can English describe it to you in 30 seconds...coding (in C/C++) would take me another 5-8 minutes (and, probably, be pretty damn inefficient ... but it's still a simple problem)
- twodave 9y ago
  It's way more expensive to hire a bad fit than to pass on a good fit. Also, I think I'd prefer the person who doesn't crack under pressure. Flopping an interview is more likely an indicator of lack of preparation than nerves, although nerves are such an easy scapegoat.
  - collyw 9y ago
    Not sure with the amount of sloppy code I have been maintaining for the last couple of jobs.The people appear to be able to do "clever" stuff, but have an inability to keep things simple or follow best practices.
eanzenberg 9y ago
How often do you need to write palindrome functions for your job? Checking substring in a string is a 1 liner in languages like python. I was at a final interview with FAANG. One question asked was to load a csv. I used pandas, it's a 1 liner. You could see the wretched face of the interviewer since he was expecting a with open() as f: do_some_shit and kept pushing me to write this on the board. I looked at him and said "Why? Why write your own method in a vanilla language? Give me a good reason."
- calcifer 9y ago
  > How often do you need to write palindrome functions for your job? That's like answering "how often do you need math?" to the question "what is 2+3?". It is an utterly, completely, stunningly trivial question that even a CS101 student on their first semester should be able to answer. > used pandas, it's a 1 liner. You could see the wretched face of the interviewer since he was expecting a with open() as f: do_some_shit I would be perfectly fine with the pandas answer, but my point is "csv parsing" wouldn't be my first question, I'd start with something much easier and if you managed that, I'd gladly accept pandas as a valid and then asked you to elaborate further (what does this pandas function do, how would you implement it yourself etc).
  - monksy 9y ago
    > (what does this pandas function do, how would you implement it yourself etc). What are the downsides to using pandas? Is that worth brining in that large of a library for a matter like that.
  - eanzenberg 9y ago
    I don't consider palindromes equivalent to math. Unless you mean how to index lists? That would be a valid question since there's different ways in python.
- cortesoft 9y ago
  So what is the interviewer supposed to do to find out if you can code? They want to give you a simple, straightforward task to see how you code. Of course, every simple, straightforward task is going to have an existing tool to do the job, but they aren't looking for a solution to parsing CSV, they are looking to see you code. They can't ask you a complicated problem, because they don't have the time (nor do you) to solve a real problem that requires coding. You are totally missing the point of what they are trying to ask you if you insist on using pandas for parsing CSV. Understanding the point of what you are being asked to do is critical to being a professional software developer.
CryoLogic 9y ago
I've had this question and replied with: const isPalindrome(str) { return str === str.split('').reverse().join(''); } And the post interview notes said bad performance on the isPalindrome() question since I didn't write out my own functions (interviewer did not mention to).
- calcifer 9y ago
  Personally, if you gave me this answer I would accept it and then asked you how those functions work and how you would implement them. Still trivial, but it would tell me whether you are familiar with the basics or you just memorized some stdlib functions.
- Bahamut 9y ago
  To be fair, if you wanted to do a performant implementation, this is probably a more expensive implementation. The expected response is generally for you to iterate over the string and construct a count map of how many times a character appears in a string, and then iterate over the keys of that object and have at most one odd number in the values of the count map. The interviewer probably should have probed you about performance though if their intention was to judge you on that (they're both O(n) time complexity, but split, reverse, and join are generally more intensive).
  - wheresvic1 9y ago
    Err I always thought that the expected performant response is to have two indexes 0 and length-1 and bring them to the middle checking that the values are equal :)
  - glangdale 9y ago
    I'm very confused by this answer. Have I missed a joke? Wouldn't the expected response be to iterate over half the string comparing the characters to the other half (in reverse order)? The criteria you provide seems to suggest aabbc is a palindrome.
    - Bahamut 9y ago
rightbyte 9y ago
Do you get a IDE with compiler for the palindrom question? Id say that close to 0 out off 10 engineers at work including me would get a working program without debugger or print statements. Just tried in c and got me 2 compiles to get it right. Without the output I would just present a nonworking program.
- calcifer 9y ago
  Maybe it's just me, but needing an entire IDE or a debugger to write a function that checks if a string is the same backwards seems entirely too much to me. It's a pen&paper question really.
  - tonyarkles 9y ago
    It's not just you. I use Visual Studio when I'm occasionally looking at C#, IntelliJ on the odd occasion that I'm doing Java, and otherwise it's emacs and I can't remember the last time I used a debugger for Go, Elixir, C, C++, JS, Python, Ruby, etc. Basically, unless the language's standard library is massive and over-abstracted, no IDE is necessary. There's no way I'll ever remember org.apache.some.deep.package.HttpClientBuilderFactory and its 6 constructor arguments, but "import requests; requests.get(...)" is pretty easy to write without an IDE.

haskellandchill 9y ago

The function to check palindrome will be composed of those building blocks, that's my meaning. Use those basic skills and composing them to solve a problem, such as palindrome, that's coding in the small to me. Coding in the large is project management and could be tested by a take home, but I'd rather tease it out by asking in person questions about organization, prioritization, and technology choice.

ryandrake 9y ago

Problem is: It's hard to judge the difference between someone who doesn't know what they are doing and someone who does but loses it under the extreme pressure of an interview wherein their entire future with the company is being determined by their performance on a 30 minute exercise. Throughout my career, I've been in professional situations where I was under a lot of pressure: Having to explain failures to executives, near-impossibly tight deadlines, production outages. At least I haven't had to testify in front of Congress yet. Absolutely NOTHING I've encountered in my professional day-to-day has the extreme level of pressure of a typical silicon valley job interview.

calcifer 9y ago
I understand and truly symphatize with stress the candidate is in, but someone who claims to be a "senior developer with 10 years experience" should be able to write that palindrome function in 30 whole minutes in any kind of stress scenario. Because if I hire that person, they'll be in charge of critical production systems and will face much harder problems in much more stressful situations and if they can't handle the palindrome question, I have very little confidence they can handle the actual job.
- ryandrake 9y ago
  People are strange. I can totally picture someone who is an experienced senior, a hero under the pressure of a critical production outage, yet whose brain goes into a crash loop when sitting across from someone who has the power to deny them their dream job. Not claiming to be that hero, but I have personally had those moments where I came out of the interview, and as the disorienting fog of pressure lifted during my drive home I said to myself, "WTF happened to my brain in there? I know that stuff cold!" EDIT: I think I read this one from a commenter here, but it's so true: We're interviewing people to be music composers, but judging them by their ability to be performance artists.
  - calcifer 9y ago
    Fair enough. I certainly don't claim to know the best interview method ever; simply that, in my experience, starting with trivial coding questions has a higher benefit/risk ratio then other approaches.
- monksy 9y ago
  I don't agree. They should be able to write that as a solution to resolve an issue. It should be very well understood why they're writing it. Additionally, if you want to keep going under that justification: you should also accept quick alternatives that aren't the naive approach. (i.e. bring out groovy, using bash, etc)
  - vorg 9y ago
    Even a "systems" language like Go is just as suitable for a "quick alternative" as a "scripty" language like Apache Groovy or Bash.
warrenm 9y ago
While I agree in the abstract ...honestly, it's not that hard to write at least pseudocode for problems like that regardless of the "stress" of an interview Is it reasonable to ask things like that? Maybe, maybe not. But as stressful as an interview is, it's still a basic problem (I can English describe it to you in 30 seconds...coding (in C/C++) would take me another 5-8 minutes (and, probably, be pretty damn inefficient ... but it's still a simple problem)
twodave 9y ago
It's way more expensive to hire a bad fit than to pass on a good fit. Also, I think I'd prefer the person who doesn't crack under pressure. Flopping an interview is more likely an indicator of lack of preparation than nerves, although nerves are such an easy scapegoat.
- collyw 9y ago
  Not sure with the amount of sloppy code I have been maintaining for the last couple of jobs.The people appear to be able to do "clever" stuff, but have an inability to keep things simple or follow best practices.

eanzenberg 9y ago

How often do you need to write palindrome functions for your job? Checking substring in a string is a 1 liner in languages like python. I was at a final interview with FAANG. One question asked was to load a csv. I used pandas, it's a 1 liner. You could see the wretched face of the interviewer since he was expecting a with open() as f: do_some_shit and kept pushing me to write this on the board. I looked at him and said "Why? Why write your own method in a vanilla language? Give me a good reason."

calcifer 9y ago
> How often do you need to write palindrome functions for your job? That's like answering "how often do you need math?" to the question "what is 2+3?". It is an utterly, completely, stunningly trivial question that even a CS101 student on their first semester should be able to answer. > used pandas, it's a 1 liner. You could see the wretched face of the interviewer since he was expecting a with open() as f: do_some_shit I would be perfectly fine with the pandas answer, but my point is "csv parsing" wouldn't be my first question, I'd start with something much easier and if you managed that, I'd gladly accept pandas as a valid and then asked you to elaborate further (what does this pandas function do, how would you implement it yourself etc).
- monksy 9y ago
  > (what does this pandas function do, how would you implement it yourself etc). What are the downsides to using pandas? Is that worth brining in that large of a library for a matter like that.
- eanzenberg 9y ago
  I don't consider palindromes equivalent to math. Unless you mean how to index lists? That would be a valid question since there's different ways in python.
cortesoft 9y ago
So what is the interviewer supposed to do to find out if you can code? They want to give you a simple, straightforward task to see how you code. Of course, every simple, straightforward task is going to have an existing tool to do the job, but they aren't looking for a solution to parsing CSV, they are looking to see you code. They can't ask you a complicated problem, because they don't have the time (nor do you) to solve a real problem that requires coding. You are totally missing the point of what they are trying to ask you if you insist on using pandas for parsing CSV. Understanding the point of what you are being asked to do is critical to being a professional software developer.

CryoLogic 9y ago

I've had this question and replied with: const isPalindrome(str) { return str === str.split('').reverse().join(''); } And the post interview notes said bad performance on the isPalindrome() question since I didn't write out my own functions (interviewer did not mention to).

calcifer 9y ago
Personally, if you gave me this answer I would accept it and then asked you how those functions work and how you would implement them. Still trivial, but it would tell me whether you are familiar with the basics or you just memorized some stdlib functions.
Bahamut 9y ago
To be fair, if you wanted to do a performant implementation, this is probably a more expensive implementation. The expected response is generally for you to iterate over the string and construct a count map of how many times a character appears in a string, and then iterate over the keys of that object and have at most one odd number in the values of the count map. The interviewer probably should have probed you about performance though if their intention was to judge you on that (they're both O(n) time complexity, but split, reverse, and join are generally more intensive).
- wheresvic1 9y ago
  Err I always thought that the expected performant response is to have two indexes 0 and length-1 and bring them to the middle checking that the values are equal :)
- glangdale 9y ago
  I'm very confused by this answer. Have I missed a joke? Wouldn't the expected response be to iterate over half the string comparing the characters to the other half (in reverse order)? The criteria you provide seems to suggest aabbc is a palindrome.
  - Bahamut 9y ago

rightbyte 9y ago

Do you get a IDE with compiler for the palindrom question? Id say that close to 0 out off 10 engineers at work including me would get a working program without debugger or print statements. Just tried in c and got me 2 compiles to get it right. Without the output I would just present a nonworking program.

calcifer 9y ago
Maybe it's just me, but needing an entire IDE or a debugger to write a function that checks if a string is the same backwards seems entirely too much to me. It's a pen&paper question really.
- tonyarkles 9y ago
  It's not just you. I use Visual Studio when I'm occasionally looking at C#, IntelliJ on the odd occasion that I'm doing Java, and otherwise it's emacs and I can't remember the last time I used a debugger for Go, Elixir, C, C++, JS, Python, Ruby, etc. Basically, unless the language's standard library is massive and over-abstracted, no IDE is necessary. There's no way I'll ever remember org.apache.some.deep.package.HttpClientBuilderFactory and its 6 constructor arguments, but "import requests; requests.get(...)" is pretty easy to write without an IDE.