WorldQuant Quantitative Research interview questions

I was asked to take an online test consisting of mathematical puzzles, statistics, probability and basic programming questions (e.g., what's the output of this algorithm). The math puzzles are tricky, if you have seen them before, they are very easy, otherwise they can't be solved within the given time. Following the written test were technical interviews targeted at my resume.

1 HR Interview 3 Interviewers Apply on the university career fair, after one week receive phone interview invitation. Then talking with an engineering about 25 min.Firstly, ask me to talk about my background and tell me their company mainly focus on which aspect. Then let me solve a technical question.