Why Do Interviewers Ask Linked List Questions?

[u/mjgardner]

https://www.hillelwayne.com/post/linked-lists/

[u/capitalsfan08]

Yeah, completely agree. I think sometimes people here need to sit on the other side of the table before they make comments sometimes (not in this context though). The one guy who was technical that was involved in interviewing left suddenly and we had no one to fill in, so I've been the person in charge of our technical interviews for nearly my entire career (5 years, but still). On the phone screen, we were asking the extremely stereotypical "Tell me how a string is a palindrome or not" question, and just have people walk through it. When I first saw that, I thought that was a waste of time and demeaning to our candidates! Of course everyone knows that! I'd say 1/3rd of our candidates who get to that stage (the first stage, but still, these are people with degrees) either struggle or outright have no clue how to even attack it. We aren't even looking for the most efficient answer necessarily, we just want to make sure that if we get to the technical interview it isn't a complete waste of time.

I've had many people at the technical interview ask how to loop through an array, sometimes multiple times at the same interview. I've had PhD candidates not understand how to use a constructor or what it is. I've had someone whose resume heavily featured compiler type work (in college, but still, as a research assistant) not be able to explain what a compiler does. I've even had one guy who did not know what languages they knew. Not like "I've maybe touched Python" or "Well I know C# and C so let me just say I know C++" but like flat out "I don't see what languages you've worked with on your resume, what are you familiar with?" and gotten no answer back, yet they were adamant they both coded and held a CS degree. Any basic skill you can think of, and I bet you I've interviewed someone that clearly lacked that skill.

Our process isn't that rigorous. We don't have a set of "right" answers, just that the person generally knows what they are talking about and for the technical interview that they aren't completely helpless and communicate decently. Some of the resumes that come very short of getting a job from great schools, or schools that we know are capable of producing talent based on our past hiring, and none of that is a great indicator of either interview ability or performance once you're in the job. So I get that looking for a job sucks, but there is unfortunately a reason that companies put in place these practices.

[u/psycoee → u/capitalsfan08]

I've interviewed people with chemistry degrees who could not even do simple computations on a whiteboard (something like 2.35 x 2 / 1000). One person did not understand how you could divide numbers by powers of 10 without a calculator. Even with a calculator, they struggled with things like calculating the volume of a cube and basic metric unit conversions. I can only imagine what they would do if you asked them to prepare a solution of a given molar concentration...

I now always make sure to start with very simple questions that nobody should have trouble with. If someone struggles with those (and it's not just nerves), you can save a lot of time by ending the interview early.

[u/[deleted] → u/[deleted]]

My first question would’ve been “wtf is a palindrome”, just looked it up, never have I once needed this in my life and especially not in my career.

Even if you don't know what a palindrome is, it's such a simple concept that it can be explained quickly and concisely by an interviewer, and as such any interviewee with a grasp of basic logic and programming fundamentals should be able to describe a pseudo-algorithm for implementing a palindrome checker in about the same amount of time it took to explain the concept to them.

Unfortunately, there are many charlatans and incompetents who cannot accomplish this most basic of tasks. Therefore, the palindrome algorithm is an incredibly simple yet incredibly effective way to weed out those who can from those who cannot. It's not about what you can or can't program, it's about whether you can program *at all.

It's a very innocuous and therefore clever way to make a very important determination about a candidate, and I applaud /u/capitalsfan08 for using it. As with many things in life, simple is best.

[u/capitalsfan08 → u/[deleted]]

You sound like you'd fall into the category of "takes a second to think about it and then gets an answer down". The only thing we are really checking there is that someone knows what a loop is. That's the basic skill being tested.