Can you give an example of a good practically focused question?
Apparently, the correct answer was Romanesco broccoli.
I failed the interview and briefly sank into a depression questioning everything I knew about raising young children, self-similarity and recursion.
I hope you got another job that you enjoy.
Or something like in the article where you start with a little code, and build on it to solve some problem that isn't a totally arbitrary tree traversal like most of the whiteboarding stuff seems to be.
For the coding part, I try to pick things that don't depend on someone hearing about it previously. I try to solve the problem myself in 1/3 the time I allot to the candidate since they are under pressure. Most candidates seem to struggle with simple problem though.
A simple one I have asked in C is to reverse the order of numbers in an array in place.
Hm...
int a[] = {1,2,3,4,5};
for (x = 0, y = 4; x < 5; x++, y--) {
a[x] ^= a[y]; a[y] ^= a[x]; a[x] ^= a[y];
}
But then the last question I got was 'find all word substrings in a string'. I struggled, giving a brute force answer (for each position in the string, check against dictionary and expand by one character until the end of the string), but struggled to improve on it. I didn't know about tries at the time, but even still it would be difficult for me to even try to code this on a whiteboard. Turns out it was "Google" question that was for optimizing runtime, and I cannot analyze like that on a whiteboard, unless it's obvious (nested for loops, etc.).
Anyway, after struggling and giving up with that question the next guy came in and berated me and my current employer (defense contractor). Not sure if it was because they thought I wasted their time or what. I left after that--not someone I would want to work for.
> The XOR-swap trick is an example of coders being too clever for their own good. Here, it gradually poisons the RC4 permutation with zeroes, until eventually the plaintext is just passed along in the clear.
But apparently some people can just write it all out on a whiteboard in one go.
Also if you changed this to a int *a (and a count), some people will get confused how to do this all with pointers. Asking how this would be tested is also a good question.
That assumes an odd number of elements (true in this case but not in general); I would recommend terminating when x >= y.
There are good balances. The question I ask is a real problem for a real product but quickly reduces to something small and manageable rather than getting bogged down in incredibly specific requirements.