[djb_hackernews]

Do you think you've ever had to do something as algorithmically complex as recursively walk a graph?

Sometimes these questions are used to probe the meta understanding of a candidate and using Graphs/Trees/DFS are universally understood concepts that make doing that easy.

[vonmoltke]

Define "algorithm". In the broader definition, yes. Kalman filtering, motion compensation, track association, XY-mapping, and similar signal processing algorithms. For NLP it has been various forms of statistical modeling and general multithreaded architecture and coordination.

As for the algorithms typical of computer science, not really. Searching and sorting has not been much a part of what I have done. My experience is mainly in translating math into code, often into code with real-time deadlines.