This is one of my 6 interview questions: "what is the most difficult software development challenge you had, and how did you solve it?" And then ask a few follow-up questions to probe a bit more.

Most of the people I interview have an answer that boils down to "I needed to do X, and then I found an API/JavaScript widget/SDK/whatever, and integrated it, and that did the trick". And... well... that's just not an interesting answer. I might as well say, "I had this pile of hardware which I had just bolted together, but it wasn't a working computer yet... so I took a Windows install image, ran the Windows installer, et voila!" with the same self-admiration as if I wrote Windows myself.

You don't really need people to have solved super complex or complicated problems, you need people who are *capable* of doing so. If your answer is something like, "I was seeing this horrible performance problem, it turned out we were doing an in-memory sort that was really slow, I found the issue using a code profiler, realized my language's sorting algorithm in the standard libraries was just the wrong one for this scenario, did some research, found a much better algorithm, and implemented it myself since I couldn't find an open source library with this algorithm for my language"... well, it's not *that* hard to write the code for a documented sorting algorithm, but the thought process here is outstanding. I care a lot more about this, than someone who just did a quick search for "API to solve hard problem" and wrote four lines of code to call the API.

J.Ja