Had a phone interview with the manager of the team. The interview was a mix of simple OO questions (inheritance, libraries I have used) and simple finance questions (option greeks, implied volatility).

The line was really bad; I even had to put my phone on full loudspeaker to try to understand the other guy. It was tough and stressful, as half the words were muffled (he didn't have problems understanding me, it seems).

Anyway, I got to the second round still.

Second interview, two days later, was onsite to meet five people in total, starting with a live written test on one of the strategist desks. The written test was to explain a binary tree structure and write a traversal method. I struggled too hard on those questions and was politely told after 40 minutes that the interview was over. I didn't see the other guys.

I never studied binary trees before, so I was definitely at a disadvantage. For my defense, though, binary trees were not mentioned during the phone interview, so I didn't suspect that kind of question to come up. But like I said, the line was really bad during the phone interview, so maybe they did mention it after all; I will never know.

Later, I rewrote the test at home from memory and got my code to work. It wasn't too hard in the end; you just need to work on it a little before to understand this type of logic.

Explain this binary tree and write a traversal method.