I've asked non-leet code questions that aren't directly related to the work the candidate would be doing. It's usually a smallish self-contained problem, solvable in less than a dozen lines, in about 5 to 20 minutes. What I like about it, is that it's novel enough, that I get to see the candidate think through the problem. I get a glimpse into their problem solving capability.

It's not a perfect proxy for how well they'd solve real user facing problems, but so far it has given me a decent indicator of their motivation/passion and apetite for problem solving. There's a dozen other, mostly non-coding questions in the interview, but this one has been the best predicator for me.

(The problem is closer to a more elaborate fizzbuzz with some math parts, than it is to a memorizable b-tree or other leet-code algorithm question)