I applied to a position online and then got contacted by HR to schedule a one-hour technical interview. I was then scheduled for the one-hour technical interview, and I am summarizing my experience below.

The interviewer asked me how the HashMap works and about its complexity. Then, he tried to disagree to see what I would say until we settled the dispute when I couldn't understand what he was trying to get at.

It was a coding session using code.io. The question was about checking if a binary tree was balanced. I coded it with a recursive solution, and it compiled and ran. He asked about the complexity; I said O(n), then corrected myself and said O(n^2). He disagreed, saying it's even more O(n^2) because you will call the function every time, which by definition means n^2. I let it go and said, "Okay."

Then I got an email saying that I wasn't selected for the position.