First Coding test, it was hosted in hackerrank. The problems are medium difficulty. Then one round phone interview with HR. Another technical phone interview. Onsite interview was in Chicago. I met 5 people there. Most of the problems are very easy, like went through the cv, and simple coding problem. One problem is hard, the probability of first index being 1 in the sequence 2^n. After the interview, I considered this problem carefully and found out to solve it one need some big theorems. So I thought the interviewee had no idea about how to solve it. The next week after the onsite, they require an additional phone interview. Asked some knowledge even not listed on cv. Rejected after the call.

two online OAs: one is a LeetCode medium–level coding problem, and the other consists of math brainteaser problems (you need to record your thought process). 1st round technical interview: OOP-style problems with some follow-up questions