Not defending the interview, but: It just really sucks that there are some companies out that believe that if you can rattle off an algorithm, then you must be

Not defending the interview, but: It just really sucks that there are some companies out that believe that if you can rattle off an algorithm, then you must be a good coder. The implication is (not able to do X) → (not a good coder), not the other way around. They imply: "Doing this esoteric mathematical stuff is a requirement for being a good coder. And there are more requirements." EDIT: strictly speaking, they don't even imply that. It may be they just consider this one of the many possible signals. Maybe they only count it if you pass. Again, most cases may actually well be as you describe. But some might not be.