It doesn't seem that the author actually asks candidates to code up the Tower of Hanoi in an interview. > I usually start with a fairly easy warm-up question

It doesn't seem that the author actually asks candidates to code up the Tower of Hanoi in an interview. > I usually start with a fairly easy warm-up question — some sort of a toy problem like an operation on lists or trees, often the kind of thing that has a neat recursive solution. Binary tree problems and some linked list problems often have fairly obvious recursive solutions -- perhaps that's what he's referring to. I doubt anyone would consider the Tower of Hanoi problem "easy". It's definitely an interesting one to investigate in a blog post say, or for one's own enrichment -- it seems like that's what the author is doing. Of course there's no way of knowing the author's intentions unless he himself clarifies it, but this is what I think.