I would never hire someone who would rather spend 20 minutes thumbing together a solution that may work instead of someone who would rather read available documentation and literature to find either...

    1. A trusted library that implements a complex feature
    2. A way to abstract away the need for a complex solution
    3. Feel the need to rush an implementation of a mission critical piece of code

I'd say software engineering is more about organization, abstracting, and simplification of a problem than it is about writing complex data structure implementations or complex algorithms. When you do need to implement a complex data structure or algorithm I think it's much more wise to survey available (and current) literature and implement the algorithm after thinking about the problem for a day or two then it is to attempt to implement it yourself in front of 3 people in a stressful time.

I'd expect no one I've ever worked with to be able to correctly meet any business requirement (full battery of tests, an attempt to avoid the more complex solution, documentation for the need and edge cases of an algorithm, real error messages, abstraction or library-extraction of this algorithm into a documented sub-project in our company's git server, etc) I have with a big 5 styled interview question.

It boils down to this:

    1. Your question is so simple it is stupid to ask someone who is actually qualified
    2. Your question is so complicated that anyone who would feel semi-confident in having actually solved it in 40 minutes is someone too dangerous to keep around