5 ms·

I've also used FizzBuzz at several companies, and the insane amount of people it filters out continues to boggle my mind.

by sjaak 2y ago

XorNot 2y ago
Do you tell them what the "mod" operator is before giving it? The failure rate of FizzBuzz has always struck me as depending on the idea that you can do a lot of programming and just never need that operator.
- sensanaty 2y ago
  Yeah I know how to implement FizzBuzz since it's such a meme, but I've basically never used the mod operator in real code. Maybe it comes up in more math-y code I suppose, but for most backend/frontend/SQL code I've never reached for it.
  - stefan_ 2y ago
    More mathy code like checking if a number is even or splitting a total number of seconds into minutes and seconds?
  - vundercind 2y ago
    I’ve used it for coloring alternating lines differently in UI code, and as a lazy way to log only every so many times some loop runs. I only know it well because it was covered near the beginning of one of the first programming books I picked up (on Perl 5) and it stuck with me because it seemed wild to me that they had an operator for that.
  - wruza 2y ago
    for (…) { heavy_op(); if (i % 100 == 0) { printf("not dead"); } Classic
  - kmoser 2y ago
    Depends on the application. I've written accounting software that makes use of it, along with heavy use of floor() and ceil(), including in SQL.
- eschneider 2y ago
  Even if that's so, modulus (or at least the concept of remainders) are elementary school math and any competent programmer could bang together an (inefficient) modulus operator in a few minutes. So even in a language w/o a mod operator, it's not a hard problem if you understand how to solve problems with code.
- azornathogron 2y ago
  You don't actually need mod to do fizzbuzz, even if that's the most obvious way for people who know what mod is. But without any "real" math at all you can do it with, eg, two counters and some if statements. Or if you recognise that there's a repeating pattern you can work out that pattern manually and just write code to emit it over and over.
- arethuza 2y ago
  I once worked with a guy who was an incredibly good developer and I was surprised when he didn't see anything special about the number 64 (i.e. a power of two) - turns out that he'd never done any bit fiddling type work so he hadn't had to think in those terms. It wouldn't surprise me if a lot of people hadn't heard of "mod" either....
  - dkdbejwi383 2y ago
    A huge majority of programming work is basically just CRUD stuff and other data shuffling. It’s not surprising that someone wouldn’t have needed to work with big shifting (or modulus) in that case.
    - arethuza 2y ago
      He was an expert in complex multi-organisation enterprise integration and was the go to guy to work out why horrific distributed transactions were failing... He also did a lot of cool stuff as side projects in his own time - just none of them happened to involve worrying about powers of 2.
- sjaak 2y ago
  No but I permit internet access as long as they don't search for the solution (I trust them not to do that, and don't monitor what they do)
  - DonHopkins 2y ago
    You're too trusting.
    - ownagefool 2y ago
      Whilst I agree, his point still stands that either they do it fast or never.
- daemin 2y ago
  Unless you specifically want a compiling and running version of FizzBuzz you don't actually need to use or know about the mod operator. At least for me it would be sufficient if the person used a function like IsMultipleOf(x, m), or Remainder(x, n). This would at least make it clear what the function did even if they didn't get the exact operator. The other thing to note is that the mod operator works differently on different languages and platforms.
  - DonHopkins 2y ago
    > the mod operator works differently on different languages and platforms Not with positive inputs, which is the domain of FizzBuzz. Even if you don't know what "mod" means, if you have no idea know what a remainder is, and that the problem calls for it, and you can't derive the mod operator using integer addition, subtraction, multiplication, and division, then your math and problem solving skills are pretty weak, which FizzBuzz tests.
- ownagefool 2y ago
  I stopped using fizz buzz a long time ago. 90% of candidates can't define a 2d array in their chosen language without first filtering the candidates, where you get to about 50%.
piva00 2y ago
Same experience, used FizzBuzz at many places and always got surprised by the amount of people it can filter. The best interview process I've ever ran at a company consisted of a basic FizzBuzz for about 15-30 min followed by a pairing session no longer than 1h30m on a problem that could get as tricky as we wanted to assess their skill level. We would both test the basics as well as go through with the candidate on how they think, how they collaborate, help them out if we felt nervousness was impacting them showing their skills, and in the end got a much better grasp on how skilled they were than if we were looking at Github repos or giving DS&A trivias to solve.
arethuza 2y ago
I once froze in an interview when asked a simple technical question - I'd been giving a presentation for an hour on how to launch a new product and I was asked by the CEO how to do something technically trivial - my brain could not do it. So he probably thought I was some marketeer pretending to be technical - which isn't really true. I suspect quite a lot of people who are labelled as "can't code" are freezing like I did.
- sjaak 2y ago
  When I ask people to code FizzBuzz I: - give them ~30 minutes on their own machine - they get to pick the language they code in - I leave the room for large parts of it - I bring them a drink - I tell them I want to see what they can do and that I don't care if they complete it - permit them to search on the internet (as long as they don't copy/paste a solution) I see this usually: - they finish in a few minutes - they just can't do it, even with hints
  - arethuza 2y ago
    Yes that sounds pretty sensible. Do you ever have a conversation with these people as to why they think they couldn't do it?
  - johnnyanmac 2y ago
    > permit them to search on the internet really? they get 30 minutes + internet and they couldn't google "javascript how to get divisible by 3"? That's just bad research at that point.
- ownagefool 2y ago
  I suspect some do, and some will be a lot when you bunch them all together. However, counter point, I've had people forced on me through much of my career who just can't code for the most part, and despite being pretty reasonable about it ( it's part of the nature of the work I do ), I'm very rarely surprised by competency.
hcrean 2y ago
I failed FizzBuzz the first time someone gave it to me in an interview... The specific failure was that I first attempted to solve by using repeated subtraction. The guy kept asking me to "solve it a different way", or saying "there is a better way to solve this". I tried using arithmetic tables, I tried using results about base10 remainders and I even tried using one of the corollaries to Fermat's little theorem to speed it up for larger inputs... every time I was told I was getting it wrong because "there was a better solution". In the end he pointed out that the only solution he would accept was use of the mod operator. Since then I have actively kept a tally: I naturally use the mod operator an average of twice a calendar year, it has always been in personal life code when dealing with complicated geometry problems, the bit of code containing it almost always fails on some edgecase because at the point of using mod it is convoluted.
- johnnyanmac 2y ago
  Honestly sounds like a bad interviewer. repeated subtraction is a good first step and I would try to push more if that was the first implementation. But If you could derive a base 10 remainder you know conceptually what problem the mod operator is trying to solve. a % b = a - (b * a/b) /assuming a sane language with integer division, else cast a/b to int/ Figuring the above operation (or getting close) is when you should more or less pass, and That's a good point to show the interviewee what the operation is. That should be the point of an interview problem, to show the thought process, not that you know fancy tricks. But alas, I was shown an XOR swap in an interview last week and spent 3 minutes deriving it on paper instead of 3 seconds saying "oh yeah, a => b and b => a" to a trick that I haven't seen since college some decade ago. The current market loves tricksters, I suppose. And yes, the actual real world use of modulo is surprisingly sparse, despite easily imagining situations where you could use it.
  - hcrean 2y ago
    I am highly reluctant to use type casting as a mathematical function!! I was burnt by early languages struggling with this problem... Even modern languages still have issues with this! Try running this in Python3.11 ``` float(9007199254740993) == int(9007199254740992) ```
CoastalCoder 2y ago
Some years ago I was remotely interviewing at Google, and I was asked to code up the reversal of a linked list. But my brain just froze. This is something I can easily solve in 5-10 minutes, correctly handling every plausible corner-case. I'm curious how common this is, statistically speaking. I'm also curious how it correlates with other things about the interviewee.

I've also used FizzBuzz at several companies, and the insane amount of people it filters out continues to boggle my mind.

by sjaak 2y ago

I've also used FizzBuzz at several companies, and the insane amount of people it filters out continues to boggle my mind.

XorNot 2y ago

Do you tell them what the "mod" operator is before giving it? The failure rate of FizzBuzz has always struck me as depending on the idea that you can do a lot of programming and just never need that operator.

sensanaty 2y ago
Yeah I know how to implement FizzBuzz since it's such a meme, but I've basically never used the mod operator in real code. Maybe it comes up in more math-y code I suppose, but for most backend/frontend/SQL code I've never reached for it.
- stefan_ 2y ago
  More mathy code like checking if a number is even or splitting a total number of seconds into minutes and seconds?
- vundercind 2y ago
  I’ve used it for coloring alternating lines differently in UI code, and as a lazy way to log only every so many times some loop runs. I only know it well because it was covered near the beginning of one of the first programming books I picked up (on Perl 5) and it stuck with me because it seemed wild to me that they had an operator for that.
- wruza 2y ago
  for (…) { heavy_op(); if (i % 100 == 0) { printf("not dead"); } Classic
- kmoser 2y ago
  Depends on the application. I've written accounting software that makes use of it, along with heavy use of floor() and ceil(), including in SQL.
eschneider 2y ago
Even if that's so, modulus (or at least the concept of remainders) are elementary school math and any competent programmer could bang together an (inefficient) modulus operator in a few minutes. So even in a language w/o a mod operator, it's not a hard problem if you understand how to solve problems with code.
azornathogron 2y ago
You don't actually need mod to do fizzbuzz, even if that's the most obvious way for people who know what mod is. But without any "real" math at all you can do it with, eg, two counters and some if statements. Or if you recognise that there's a repeating pattern you can work out that pattern manually and just write code to emit it over and over.
arethuza 2y ago
I once worked with a guy who was an incredibly good developer and I was surprised when he didn't see anything special about the number 64 (i.e. a power of two) - turns out that he'd never done any bit fiddling type work so he hadn't had to think in those terms. It wouldn't surprise me if a lot of people hadn't heard of "mod" either....
- dkdbejwi383 2y ago
  A huge majority of programming work is basically just CRUD stuff and other data shuffling. It’s not surprising that someone wouldn’t have needed to work with big shifting (or modulus) in that case.
  - arethuza 2y ago
    He was an expert in complex multi-organisation enterprise integration and was the go to guy to work out why horrific distributed transactions were failing... He also did a lot of cool stuff as side projects in his own time - just none of them happened to involve worrying about powers of 2.
sjaak 2y ago
No but I permit internet access as long as they don't search for the solution (I trust them not to do that, and don't monitor what they do)
- DonHopkins 2y ago
  You're too trusting.
  - ownagefool 2y ago
    Whilst I agree, his point still stands that either they do it fast or never.
daemin 2y ago
Unless you specifically want a compiling and running version of FizzBuzz you don't actually need to use or know about the mod operator. At least for me it would be sufficient if the person used a function like IsMultipleOf(x, m), or Remainder(x, n). This would at least make it clear what the function did even if they didn't get the exact operator. The other thing to note is that the mod operator works differently on different languages and platforms.
- DonHopkins 2y ago
  > the mod operator works differently on different languages and platforms Not with positive inputs, which is the domain of FizzBuzz. Even if you don't know what "mod" means, if you have no idea know what a remainder is, and that the problem calls for it, and you can't derive the mod operator using integer addition, subtraction, multiplication, and division, then your math and problem solving skills are pretty weak, which FizzBuzz tests.
ownagefool 2y ago
I stopped using fizz buzz a long time ago. 90% of candidates can't define a 2d array in their chosen language without first filtering the candidates, where you get to about 50%.

piva00 2y ago

Same experience, used FizzBuzz at many places and always got surprised by the amount of people it can filter. The best interview process I've ever ran at a company consisted of a basic FizzBuzz for about 15-30 min followed by a pairing session no longer than 1h30m on a problem that could get as tricky as we wanted to assess their skill level. We would both test the basics as well as go through with the candidate on how they think, how they collaborate, help them out if we felt nervousness was impacting them showing their skills, and in the end got a much better grasp on how skilled they were than if we were looking at Github repos or giving DS&A trivias to solve.

arethuza 2y ago

I once froze in an interview when asked a simple technical question - I'd been giving a presentation for an hour on how to launch a new product and I was asked by the CEO how to do something technically trivial - my brain could not do it. So he probably thought I was some marketeer pretending to be technical - which isn't really true. I suspect quite a lot of people who are labelled as "can't code" are freezing like I did.

sjaak 2y ago
When I ask people to code FizzBuzz I: - give them ~30 minutes on their own machine - they get to pick the language they code in - I leave the room for large parts of it - I bring them a drink - I tell them I want to see what they can do and that I don't care if they complete it - permit them to search on the internet (as long as they don't copy/paste a solution) I see this usually: - they finish in a few minutes - they just can't do it, even with hints
- arethuza 2y ago
  Yes that sounds pretty sensible. Do you ever have a conversation with these people as to why they think they couldn't do it?
- johnnyanmac 2y ago
  > permit them to search on the internet really? they get 30 minutes + internet and they couldn't google "javascript how to get divisible by 3"? That's just bad research at that point.
ownagefool 2y ago
I suspect some do, and some will be a lot when you bunch them all together. However, counter point, I've had people forced on me through much of my career who just can't code for the most part, and despite being pretty reasonable about it ( it's part of the nature of the work I do ), I'm very rarely surprised by competency.

hcrean 2y ago

I failed FizzBuzz the first time someone gave it to me in an interview... The specific failure was that I first attempted to solve by using repeated subtraction. The guy kept asking me to "solve it a different way", or saying "there is a better way to solve this". I tried using arithmetic tables, I tried using results about base10 remainders and I even tried using one of the corollaries to Fermat's little theorem to speed it up for larger inputs... every time I was told I was getting it wrong because "there was a better solution". In the end he pointed out that the only solution he would accept was use of the mod operator. Since then I have actively kept a tally: I naturally use the mod operator an average of twice a calendar year, it has always been in personal life code when dealing with complicated geometry problems, the bit of code containing it almost always fails on some edgecase because at the point of using mod it is convoluted.

johnnyanmac 2y ago
Honestly sounds like a bad interviewer. repeated subtraction is a good first step and I would try to push more if that was the first implementation. But If you could derive a base 10 remainder you know conceptually what problem the mod operator is trying to solve. a % b = a - (b * a/b) /assuming a sane language with integer division, else cast a/b to int/ Figuring the above operation (or getting close) is when you should more or less pass, and That's a good point to show the interviewee what the operation is. That should be the point of an interview problem, to show the thought process, not that you know fancy tricks. But alas, I was shown an XOR swap in an interview last week and spent 3 minutes deriving it on paper instead of 3 seconds saying "oh yeah, a => b and b => a" to a trick that I haven't seen since college some decade ago. The current market loves tricksters, I suppose. And yes, the actual real world use of modulo is surprisingly sparse, despite easily imagining situations where you could use it.
- hcrean 2y ago
  I am highly reluctant to use type casting as a mathematical function!! I was burnt by early languages struggling with this problem... Even modern languages still have issues with this! Try running this in Python3.11 ``` float(9007199254740993) == int(9007199254740992) ```

CoastalCoder 2y ago

Some years ago I was remotely interviewing at Google, and I was asked to code up the reversal of a linked list. But my brain just froze. This is something I can easily solve in 5-10 minutes, correctly handling every plausible corner-case. I'm curious how common this is, statistically speaking. I'm also curious how it correlates with other things about the interviewee.