Calculate big O notation I'm a bit unsure how to determine the big O notation of the following terms: 
$\sqrt n\ $ + $\log n\ $
Is the big O notation O($\sqrt n\ $) or O ($\sqrt n\ $ + $\log n\ $)? 
It's clear that $\sqrt n\ $ grows faster than $\log n\ $ but I'm uncertain, if it's enough to express that with O($\sqrt n\ $). 
Thanks in advance!

If you think of $\mathcal O(\sqrt n)$ and $\mathcal O(\sqrt n + \log n)$ as sets of functions, they are exactly the same set. Thus, saying that the function $\sqrt n + \log n$ is $O(\sqrt n)$ is true, but saying that it is $O(\sqrt n + \log n)$ is also true. Typically, though, the former is preferred, since it's the simpler expression.
