Jane Street Software Engineer - Intern interview questions

first there's a 10-15 min call with a recruiter (another form of screening i guess) where you talk about your background and experiences. then if you pass that, an online interview. if you pass it too, there are 3 on-site interviews (they pay for everything), 2 before lunch and one after.

First round was a simple OOP question, building up in difficulty as you get previous parts right Next round questions were more difficult but of the same nature with 2 engineers