Robinhood Back-End Engineering interview questions

1. I received an employee referral 2. I was contacted about doing the coding challenge 3. Technical phone interview with SWE 4. They flew me out to Menlo Park 4a. Algorithm interview with SWE - Extremely difficult but I got the best solution 4b. Coding interview with SWE - a lot of questions about your actual code, how you would improve it, etc...