4 ms·

How to ace your next job interview

23 points by Maciej001 9y ago

dominotw 9y ago
My phone screen interviewer asked me this week to implement exponentiation function without using multiplication or addition. How do i prepare for that :\ ?
- jonathanstrange 9y ago
  That's a difficult format, because the phone interview does not allow you to assert dominance by pissing at the corner of the interviewer's office desk.
- mpeg 9y ago
  IMHO if it's for a senior engineer position, you should at least be able to explain how that would be implemented (bitwise operations) even if you wouldn't get it right in a whiteboard.
  - sidlls 9y ago
    You're not talking about an engineering problem, first of all (assuming it's a software implementation being talked about, of course). Secondly, it's difficult for me to see how this particular problem is a good motivation for discussion about the use of bitwise operations in general. I've written code in low level game engines, real time computational systems, physics and for drivers. The first and last items are the only ones where bitwise operations of this sort were even necessary to consider. Unless this problem is for a job working on calculations on hardware that only supplies bitwise ops, it's a math trivia problem disguised as a coding interview question.
  - always_good 9y ago
    Depends on the job. Aside from having to port an algorithm, I'm pretty sure the last time I used a bitwise operator seriously in 10 years was back in uni.
  - Double_a_92 9y ago
    Could you explain it to us? Thx. I know how bitwise operators works and have a CS degree... But even with googling I couldn't find a straight forward way to implement a general exponential operator using only bit operations.
    - bmay 9y ago
      You need some cleverness to code an add(x, y) method with only bitwise operators. Then, you need to code a multiply(x, y) method using some more bit shifting cleverness and your new add method. Then, do repeated squaring using your new multiply method.
      - foldr 9y ago
        Sure, but that's not a very satisfying answer because it doesn't rely on any special insight about how exponention works. It would be better to just ask someone to code up addition and/or multiplication using bitwise operations if that's what you want to test. That's sort of a reasonable question in the case of addition. Asking someone to implement multiplication using bitwise operations in a phone interview would be pretty crazy, though.
- deanmen 9y ago
  exponentiation be repeated squaring, multiplication by shift and add, then addition by subtraction "x - (- y)" or concatenating strings of the appropriate lengths (use printf in c), or bitwise operations
- robinwassen 9y ago
  Subtract and negations :)
  - hvidgaard 9y ago
    If you start by using subtraction, I'm sure the interviewer will say that is disallowed as well. They're fishing for something else.
  - bmay 9y ago
    Better yet: repeatedly divide and then take the inverse.
- extrememacaroni 9y ago
  You read up on using bitwise operations to perform the usual ones, "how about you do some multiplication without actual multiplication" is one of the main interview inventions you want to know how to handle.
  - foldr 9y ago
    There's no straightforward way of implementing a general exponentiation function using only bitwise operations. Of course it is straightforward to compute 2^x for x an integer >= 0, or x*2, but it's not clear that this is the question that was posed.
- xedarius 9y ago
  Seems pretty harsh to me, and had you successfully answered that question I'm not quite sure what they'd have learnt. If I were put on the spot with those constraints I'd suggest a lookup table. I'm currently looking for a new job, however I tend to ask about the process upfront, if it sounds like a wanky anal probe type of interview I simply withdraw from the process. Which is sad, as some of the jobs I'd really like.
- sin7 9y ago
  Nested for loop. Count the cycles.
- kafkaesq 9y ago
  You don't. You simply allow whatever perfectly natural reaction your spinal cord chooses to trigger - to bubble up through your system. Which you should in no way be ashamed of. You're the one coming to them on good faith, expecting to be treated as a professional, after all. And they're the one who, unfortunately, has chosen to revert to silly mind games, and demonstrate a complete and obvious lack of respect for your time. The only way to "prepare" for situations like these is to go in with a willingness to trust one's own gut - and to simply break off the interview once you start to feel you're not being treated professionally, and that the questions you're being asked are, like the above, completely out of line.† † Okay, maybe if you were applying for the job of chairing some IEEE committee on numerical standards or something, thiis particular question might be. But I somehow doubt that was the case with this particular role.
  - kafkaesq 9y ago
    EDIT: "this particular question might be" => "... might be applicable."
gizmodo59 9y ago
The stock images are just distracting and makes me not to take the points mentioned seriously.
- hardlianotion 9y ago
  The text isn’t a great deal more helpful
pleasecalllater 9y ago
As 90% of recruiters I meet start with asking for a required salary (and 40% of them end on that question) just say that you will work for free :)
FLUX-YOU 9y ago
If you get anxious in interviews, don't read this article. Consciously thinking about your body language (and you will if you aren't practiced at it) will hinder you from having a good conversation. Body language is not a criteria that interviewers should seriously be looking at unless you are hiring someone that will be representing the company publicly or it's a high-level position: PR, executives, marketing, etc.
- anonemouse145 9y ago
  They shouldn't be. But unless the people interviewing you aren't mammals, they are. Instead of thinking about your physical cues and freezing, you should do some mirror practice or have a trusted person watch you and give tips until your worst habits are corrected. Once you can naturally sit up straight and look smart as you mull over questions, ignore the rest of this article.
- deleted 9y ago
  [deleted]
Jedd 9y ago
We seem to have a lot of unhelpfully rude comments about TFA, and why it doesn't apply to or help in their specific situations. Everyone (for large values of most people) thinks that they are normal, and that everyone they interact with has a comparable, rational evaluation mechanism. Disabusing this notion - and providing some simple ideas to consider when interacting with people who don't know you, but from whom you seek favour - is one of the more useful aspects of articles like this.

23 points by Maciej001 9y ago

My phone screen interviewer asked me this week to implement exponentiation function without using multiplication or addition. How do i prepare for that :\ ?

jonathanstrange 9y ago
That's a difficult format, because the phone interview does not allow you to assert dominance by pissing at the corner of the interviewer's office desk.
mpeg 9y ago
IMHO if it's for a senior engineer position, you should at least be able to explain how that would be implemented (bitwise operations) even if you wouldn't get it right in a whiteboard.
- sidlls 9y ago
  You're not talking about an engineering problem, first of all (assuming it's a software implementation being talked about, of course). Secondly, it's difficult for me to see how this particular problem is a good motivation for discussion about the use of bitwise operations in general. I've written code in low level game engines, real time computational systems, physics and for drivers. The first and last items are the only ones where bitwise operations of this sort were even necessary to consider. Unless this problem is for a job working on calculations on hardware that only supplies bitwise ops, it's a math trivia problem disguised as a coding interview question.
- always_good 9y ago
  Depends on the job. Aside from having to port an algorithm, I'm pretty sure the last time I used a bitwise operator seriously in 10 years was back in uni.
- Double_a_92 9y ago
  Could you explain it to us? Thx. I know how bitwise operators works and have a CS degree... But even with googling I couldn't find a straight forward way to implement a general exponential operator using only bit operations.
  - bmay 9y ago
    You need some cleverness to code an add(x, y) method with only bitwise operators. Then, you need to code a multiply(x, y) method using some more bit shifting cleverness and your new add method. Then, do repeated squaring using your new multiply method.
    - foldr 9y ago
      Sure, but that's not a very satisfying answer because it doesn't rely on any special insight about how exponention works. It would be better to just ask someone to code up addition and/or multiplication using bitwise operations if that's what you want to test. That's sort of a reasonable question in the case of addition. Asking someone to implement multiplication using bitwise operations in a phone interview would be pretty crazy, though.
deanmen 9y ago
exponentiation be repeated squaring, multiplication by shift and add, then addition by subtraction "x - (- y)" or concatenating strings of the appropriate lengths (use printf in c), or bitwise operations
robinwassen 9y ago
Subtract and negations :)
- hvidgaard 9y ago
  If you start by using subtraction, I'm sure the interviewer will say that is disallowed as well. They're fishing for something else.
- bmay 9y ago
  Better yet: repeatedly divide and then take the inverse.
extrememacaroni 9y ago
You read up on using bitwise operations to perform the usual ones, "how about you do some multiplication without actual multiplication" is one of the main interview inventions you want to know how to handle.
- foldr 9y ago
  There's no straightforward way of implementing a general exponentiation function using only bitwise operations. Of course it is straightforward to compute 2^x for x an integer >= 0, or x*2, but it's not clear that this is the question that was posed.
xedarius 9y ago
Seems pretty harsh to me, and had you successfully answered that question I'm not quite sure what they'd have learnt. If I were put on the spot with those constraints I'd suggest a lookup table. I'm currently looking for a new job, however I tend to ask about the process upfront, if it sounds like a wanky anal probe type of interview I simply withdraw from the process. Which is sad, as some of the jobs I'd really like.
sin7 9y ago
Nested for loop. Count the cycles.
kafkaesq 9y ago
You don't. You simply allow whatever perfectly natural reaction your spinal cord chooses to trigger - to bubble up through your system. Which you should in no way be ashamed of. You're the one coming to them on good faith, expecting to be treated as a professional, after all. And they're the one who, unfortunately, has chosen to revert to silly mind games, and demonstrate a complete and obvious lack of respect for your time. The only way to "prepare" for situations like these is to go in with a willingness to trust one's own gut - and to simply break off the interview once you start to feel you're not being treated professionally, and that the questions you're being asked are, like the above, completely out of line.† † Okay, maybe if you were applying for the job of chairing some IEEE committee on numerical standards or something, thiis particular question might be. But I somehow doubt that was the case with this particular role.
- kafkaesq 9y ago
  EDIT: "this particular question might be" => "... might be applicable."

gizmodo59 9y ago

The stock images are just distracting and makes me not to take the points mentioned seriously.

hardlianotion 9y ago
The text isn’t a great deal more helpful

pleasecalllater 9y ago

As 90% of recruiters I meet start with asking for a required salary (and 40% of them end on that question) just say that you will work for free :)

FLUX-YOU 9y ago

If you get anxious in interviews, don't read this article. Consciously thinking about your body language (and you will if you aren't practiced at it) will hinder you from having a good conversation. Body language is not a criteria that interviewers should seriously be looking at unless you are hiring someone that will be representing the company publicly or it's a high-level position: PR, executives, marketing, etc.

anonemouse145 9y ago
They shouldn't be. But unless the people interviewing you aren't mammals, they are. Instead of thinking about your physical cues and freezing, you should do some mirror practice or have a trusted person watch you and give tips until your worst habits are corrected. Once you can naturally sit up straight and look smart as you mull over questions, ignore the rest of this article.
deleted 9y ago
[deleted]

Jedd 9y ago

We seem to have a lot of unhelpfully rude comments about TFA, and why it doesn't apply to or help in their specific situations. Everyone (for large values of most people) thinks that they are normal, and that everyone they interact with has a comparable, rational evaluation mechanism. Disabusing this notion - and providing some simple ideas to consider when interacting with people who don't know you, but from whom you seek favour - is one of the more useful aspects of articles like this.