[louthy]

> but about as useful to a software engineering project in most cases as the ability to smelt and construct a screw is to an automobile engineer

I strongly disagree. Having a deeper understanding of how the data structures you use day-to-day (whether or not you implemented them or not) is vital to you picking the correct structure for any particular task. Not knowing the basics of how to implement a binary tree, a singly or doubly linked list is a massive red flag in terms of the competence of a candidate in my humble opinion.

I think absolutely there are classes of data structures that are obscure or leftfield that shouldn't be asked of a candidate, but there's a hell of a lot that a professional should know, regardless of whether they're using a library that does it for them.

[jancsika]

> Not knowing the basics of how to implement a binary tree, a singly or doubly linked list is a massive red flag in terms of the competence of a candidate in my humble opinion.

I agree.

On the flip side-- upon successfully implementing a linked list, a clever candidate might let it slip that he/she designed the interface to be performant with a particular use case in mind, and that they weren't sure if the interview had the same expectation for that use case. If the interviewer consequently signaled agreement with the premise that linked lists have performance benefits in certain cases, it's a good indicator that the people in charge probably aren't thinking critically about the software they are producing.

[lttlrck]

Is having a deeper than big-O understanding of data structure truely necessary?

A mechanical engineer will have an understanding the characteristics of different screws (tensile strength, corrosion resistance, material compatibly etc) enabling them to pick the right one for the task at hand. Understanding the crystalline structure and the ability to smelt one yourself is likely out of scope and probably predefined by domains experts.

Why can’t software work like this?

[rnprince]

By the time you've memorized all the cases where a binary tree does and doesn't make sense, you might as well have just learned how they work.

[louthy]

Exactly. I'd be very wary of any professional that hadn't had the intellectual curiosity to at least understand how they work, never mind actually try to implement one.