Most common phone interview question at Google
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Most common phone interview question at Google
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Re: Most common phone interview question at Google
#2> This means is a magnitude faster than the previous one!
Is this right? It's a quadratic not an order of magnitude difference isn't it? And can you be an order of magnitude faster in an O notation expression anyway? Isn't an order of magnitude a coefficient? Don't we drop coefficients in O notation?
Re: Most common phone interview question at Google
#3Congrats, it's now off the list of phone interview questions at Google.
Re: Most common phone interview question at Google
#4I used to use this question before it became too common. Any reasonably-well-prepared candidate should be able come up with the O(N) solution and the follow-up is always good for a discussion: "what if the string is huge but the alphabet is small? Eg, a DNA sequence."
There's a single pass solution that's left as an exercise for the reader.
Re: Most common phone interview question at Google
#5I used to use this question before it became too common. Any reasonably-well-prepared candidate should be able come up with the O(N) solution and the follow-up is always good for a discussion: "what if the string is huge but the alphabet is small? Eg, a DNA sequence." There's a single pass solution that's left as an exercise for the reader.
> Any reasonably-well-prepared candidate
Isn't that the point? You say it like it's a problem, but it screens for someone who's reasonably prepared, which is probably what Google wants to do because they really start looking for the super-world-tier people they employ, because I guess that takes more time and resources.
> There's a single pass solution that's left as an exercise for the reader.
Doesn't the blog post already include a single-pass solution that works on a small alphabet?
Re: Most common phone interview question at Google
#6I love that this question is very basic, tests only entry-level data structures, and can at least be talked and reasoned about even if you don't know the exact API of a hashmap, and YET I am sure people will find a reason to complain about this claiming they never actually need to find a recurring character in their actual job role.
Re: Most common phone interview question at Google
#7Usually, part of the question is to ask about legal characters. If they tell you it's letters only, then you can get away with a pre-allocated array (and give a concrete big O answer).
Re: Most common phone interview question at Google
#8> This means is a magnitude faster than the previous one! Is this right? It's a quadratic not an order of magnitude difference isn't it? And can you be an order of magnitude faster in an O notation expression anyway? Isn't an order of magnitude a coefficient? Don't we drop coefficients in O notation?
> Is this right?
It's not right, indeed
Re: Most common phone interview question at Google
#9> This means is a magnitude faster than the previous one! Is this right? It's a quadratic not an order of magnitude difference isn't it? And can you be an order of magnitude faster in an O notation expression anyway? Isn't an order of magnitude a coefficient? Don't we drop coefficients in O notation?
It's not wrong! For some value of N it is an order of magnitude faster. It's just a bit misleading.
Re: Most common phone interview question at Google
#10> This means is a magnitude faster than the previous one! Is this right? It's a quadratic not an order of magnitude difference isn't it? And can you be an order of magnitude faster in an O notation expression anyway? Isn't an order of magnitude a coefficient? Don't we drop coefficients in O notation?
It's definitely wrong. A lot of people use "order of magnitude" to just mean "a lot".
I always use the precise meaning. It might be better for me to say "factor of ten" rather than "order of magnitude" if other people don't always use the precise meaning.