4 ms·

If you are faced with a question like this in a Google interview, and you simply state the answer above right away, you are only solving part of the problem. A

If you are faced with a question like this in a Google interview, and you simply state the answer above right away, you are only solving part of the problem. A Google interviewer expects you to ask questions and clarify any simplifying assumptions you may have made. For eg: Are you assuming right at the beginning that the entire tree fits in memory? If so, Google interviewers expect you to clarify that at the beginning. They might later ask you to modify your solution for cases where your assumptions don't hold true. From what I know, the biggest mistake people make during tech interviews with the big 5 is directly jumping to solutions without probing deeper. At the scale at which the big 5 operate, many routinely simple assumptions can be problematic.

kazinator 9y ago
If a tree is so big it doesn't fit into memory, what are you trying to achieve by swapping it? How about just working with the original tree the way it is and just traversing it in reverse order, if necessary. I would probably ask if this is in-place or do we treat the input tree as immutable.
- saagarjha 9y ago
  > I would probably ask if this is in-place or do we treat the input tree as immutable. …that's what the parent comment is implying. Ask questions and don't assume things.
  - kazinator 9y ago
    If you can code a prototype as fast as asking question, why not. Code it up and then ask, "how about this: what requirements are missing from this that require changes or a rewrite?" Asking too many questions sounds like you're trying to delay coding something up. Suppose you just ask questions and they pile on more the requirements. Then the combination of requirements makes it so hard that you can't really code anything on a whiteboard. You're hosed. If you incrementally prototype, at least you arrive at the same point having some iterations of code on the whiteboard.
    - sumitgt 9y ago
      I'm sorry, this is terrible advice. Trust me, the interviewer is never gonna pile up requirements on you. In fact, they are trained to ensure that what they ask can be completed in the time allotted (with time to spare for candidate's questions). More often than not, when you ask clarifying questions, you will end up with a much different problem (and sometimes simpler) than what you expected. > Asking too many questions sounds like you're trying to delay coding something up. No it doesn't. > If you can code a prototype as fast as asking question, why not. Code it up and then ask, "how about this: what requirements are missing from this that require changes or a rewrite?" This is terrible, you are now making the interviewer do your work. You need to tell the interviewer what the boundary conditions of your solution are. That gives valuable data about your understanding of the solution space.
      - kazinator 9y ago
        > you are now making the interviewer do your work. To clarify, by "what requirements are missing" I don't mean "what is wrong with my code" (as in, in what way does it not meet the requirements that were already given; please debug my code for missed requirements). Of course the properties of the solution are clear and remarks are made about that in the course of writing it up and discussing. The "what requirements are missing" question is purely about new/different requirements.
    - saagarjha 9y ago
      > Asking too many questions sounds like you're trying to delay coding something up. In my experience, if you write boilerplate you'd need to write anyways while asking these questions interviewers don't hold it against you.
rurban 9y ago
No, this is not what happened at my google interview. Some poor HR guy, without any tech background read questions from his screen, and tried to match my answers with his answers. When I gave a too good answer on something he said "no wrong, next question". Ridiculous interviews. Twice. That's why I can relate to Max Howell.
- sumitgt 9y ago
  That's just the HR screen. The actual interviews are not like that.

kazinator 9y ago

If a tree is so big it doesn't fit into memory, what are you trying to achieve by swapping it? How about just working with the original tree the way it is and just traversing it in reverse order, if necessary. I would probably ask if this is in-place or do we treat the input tree as immutable.

saagarjha 9y ago
> I would probably ask if this is in-place or do we treat the input tree as immutable. …that's what the parent comment is implying. Ask questions and don't assume things.
- kazinator 9y ago
  If you can code a prototype as fast as asking question, why not. Code it up and then ask, "how about this: what requirements are missing from this that require changes or a rewrite?" Asking too many questions sounds like you're trying to delay coding something up. Suppose you just ask questions and they pile on more the requirements. Then the combination of requirements makes it so hard that you can't really code anything on a whiteboard. You're hosed. If you incrementally prototype, at least you arrive at the same point having some iterations of code on the whiteboard.
  - sumitgt 9y ago
    I'm sorry, this is terrible advice. Trust me, the interviewer is never gonna pile up requirements on you. In fact, they are trained to ensure that what they ask can be completed in the time allotted (with time to spare for candidate's questions). More often than not, when you ask clarifying questions, you will end up with a much different problem (and sometimes simpler) than what you expected. > Asking too many questions sounds like you're trying to delay coding something up. No it doesn't. > If you can code a prototype as fast as asking question, why not. Code it up and then ask, "how about this: what requirements are missing from this that require changes or a rewrite?" This is terrible, you are now making the interviewer do your work. You need to tell the interviewer what the boundary conditions of your solution are. That gives valuable data about your understanding of the solution space.
    - kazinator 9y ago
      > you are now making the interviewer do your work. To clarify, by "what requirements are missing" I don't mean "what is wrong with my code" (as in, in what way does it not meet the requirements that were already given; please debug my code for missed requirements). Of course the properties of the solution are clear and remarks are made about that in the course of writing it up and discussing. The "what requirements are missing" question is purely about new/different requirements.
  - saagarjha 9y ago
    > Asking too many questions sounds like you're trying to delay coding something up. In my experience, if you write boilerplate you'd need to write anyways while asking these questions interviewers don't hold it against you.

rurban 9y ago

No, this is not what happened at my google interview. Some poor HR guy, without any tech background read questions from his screen, and tried to match my answers with his answers. When I gave a too good answer on something he said "no wrong, next question". Ridiculous interviews. Twice. That's why I can relate to Max Howell.

sumitgt 9y ago
That's just the HR screen. The actual interviews are not like that.