One property of the Big-O-notation is the sum rule, which states that when I have two functions $f1$ and $f2$ and their corresponding complexity functions are $g1$ and $g2$, then the combined complexity is $f1 + f2 = O(max(g1, g2))$.
But what do we pick if both complexity-functions are equal? E.g., if $f1(n)$ is the sorting of an array and $f2(m)$ as well, then the complexities are $O(nlog(n))$ and $O(mlog(m))$. Applying the rule would be $O(max(nlog(n), mlog(m)))$. I think that picking any of those would yield a valid but very unintuitive estimation as you would drop one variable. Besides that, it’s not clear which one to pick.
Is it the case that you are not supposed to use the rule when there are multiple variables involved?
What formula I can use in cell C2 to import one column from sheet 2 using a drop-down list?
Here’s the document.
This was asked by Amazon in their campus dive.