Criteo Senior Software Engineer interview questions

I've applied online and passed an initial HR interview (salary expectations, why Criteo, why Paris, etc), after that I had 2 Skype interviews (~1 hour each) where I had to do a coding task online (via collabedit.com), answer some theoretical questions (garbage collector, hashcode & equals, etc) and I had an opportunity to ask a few questions about the company and the projects. After that I was invited to the office for 4 f2f interviews (2 coding interviews, design interview, an interview with management). During the coding interview I had to estimate time complexity for each solution and explain how it's scalable and how it will perform dealing with huge data volumes. After 3rd f2f interview HR informed me that they've decided not to continue.