4 ms·

Actually, i wanted to ask this question to good software engineers. I once had a coding problem interview where a half of the logic could be handled by an auto

by orwin 4y ago

Actually, i wanted to ask this question to good software engineers. I once had a coding problem interview where a half of the logic could be handled by an autobalncing tree. I\ve never really used autobalancing trees in real software before, but i knew how to make them from scratch, quickly as RB tree is a very common school problem. I spend twenty minutes choosing between coding one from scratch and picking an already existing solution. I ended up choosing gnl's RB trees, with all the makefile/autoinstall issue that i would have to fix instead. I did not gain any time, really, but i wanted to show i did not suffer the NIH syndrome. Was that a mistake? Should i stay within the stdlib during coding interviews (i don't know if they could run the code, i think the interviewer was running windows)

flohofwoe 4y ago
Depends on the interviewer I guess. Some people will be adamant to use the stdlib as much as possible because they have a war story of how something went terribly wrong by not using the stdlib, others will insist that the stdlib is rubbish because they have a war story of how something went terribly wrong by relying on the stdlib. The problem is that both are right. (but jokes aside, I guess that the interviewer is more interested in your ability to solve a problem from scratch instead of you ability to google for an existing solution - even if googling makes a lot of sense in the real world)
- benibela 4y ago
  I keep alternating between those positions And I use FreePascal. Its stdlib is vastly larger than the C++ stdlib, but also completely untested/unusable, because no one is using it. I wrote my own unicode handling functions for everything. Yesterday I found a new test case, and noticed that my convert utf8 to lowercase function did not handle the Turkish İ correctly (it should turn into two codepoints rather than one for reasons. although I had a check for that symbol, but it was in the wrong branch). And my function had quadratic runtime, so it was also nearly unusable. So I fixed my function. Then I thought, why am I even writing a convert to lowercase function? FreePascal already has a convert to lowercase function. There is a lesson here, do not write your own functions, you will miss cases. So I loaded the stdlib Unicode functions to compare my function to their function. And, segmentation fault. Not in the convert to lowercase function, but just loading that Unicode part of the stdlib broke something. Although while writing this post, I thought, perhaps I test it again, just the convert to lowercase function, without the crashing part. It also fails to handle the İ. And worse, it returns a string that is one byte too large, like a garbage null terminator. There is a lesson here, do not use the stdlib, it is just broken. Then I compared it to a compare to lowercase function from another library I had included. Twice as fast as even my new fixed function. But it also does not handle the İ symbol. There is a lesson here, do not use other libraries, they do not do what you need them to do.
  - iex_xei 4y ago
    Sorry for the İ/i I/ı bug. Even modern software in other languages fall to that trap time to time, so probably it's not handled well in other languages either.
mvgoogler 4y ago
I would ask the interviewer and use it as an opportunity to show your knowledge of data structures and your ability to reason about trade-offs and talk through priorities. I would say something like: "I think a balanced tree, such as an rb-tree, would be useful here for <reasons that make sense given the problem and the properties of rb trees>. I've written rb trees before and think I could write a basic one in 10-15 minutes or I could use <class from the std library, which uses a balanced tree>. Which would you prefer?" Assuming what you said made sense I would take an interaction like that as a positive signal.

by orwin 4y ago

flohofwoe 4y ago

Depends on the interviewer I guess. Some people will be adamant to use the stdlib as much as possible because they have a war story of how something went terribly wrong by not using the stdlib, others will insist that the stdlib is rubbish because they have a war story of how something went terribly wrong by relying on the stdlib. The problem is that both are right. (but jokes aside, I guess that the interviewer is more interested in your ability to solve a problem from scratch instead of you ability to google for an existing solution - even if googling makes a lot of sense in the real world)

benibela 4y ago
I keep alternating between those positions And I use FreePascal. Its stdlib is vastly larger than the C++ stdlib, but also completely untested/unusable, because no one is using it. I wrote my own unicode handling functions for everything. Yesterday I found a new test case, and noticed that my convert utf8 to lowercase function did not handle the Turkish İ correctly (it should turn into two codepoints rather than one for reasons. although I had a check for that symbol, but it was in the wrong branch). And my function had quadratic runtime, so it was also nearly unusable. So I fixed my function. Then I thought, why am I even writing a convert to lowercase function? FreePascal already has a convert to lowercase function. There is a lesson here, do not write your own functions, you will miss cases. So I loaded the stdlib Unicode functions to compare my function to their function. And, segmentation fault. Not in the convert to lowercase function, but just loading that Unicode part of the stdlib broke something. Although while writing this post, I thought, perhaps I test it again, just the convert to lowercase function, without the crashing part. It also fails to handle the İ. And worse, it returns a string that is one byte too large, like a garbage null terminator. There is a lesson here, do not use the stdlib, it is just broken. Then I compared it to a compare to lowercase function from another library I had included. Twice as fast as even my new fixed function. But it also does not handle the İ symbol. There is a lesson here, do not use other libraries, they do not do what you need them to do.
- iex_xei 4y ago
  Sorry for the İ/i I/ı bug. Even modern software in other languages fall to that trap time to time, so probably it's not handled well in other languages either.

mvgoogler 4y ago

I would ask the interviewer and use it as an opportunity to show your knowledge of data structures and your ability to reason about trade-offs and talk through priorities. I would say something like: "I think a balanced tree, such as an rb-tree, would be useful here for <reasons that make sense given the problem and the properties of rb trees>. I've written rb trees before and think I could write a basic one in 10-15 minutes or I could use <class from the std library, which uses a balanced tree>. Which would you prefer?" Assuming what you said made sense I would take an interaction like that as a positive signal.