Criteo Senior Software Engineer interview questions

From the very beginning I sent CV to company. Then hr contact me via skype and we approve date for interview. Later tech specialist call me and we have one or two hour interview.

Applied to a position from LinkedIn. A recruiter contacted me with some general questions. After a review of my CV Criteo organized 2 Skype interviews. During both Skype interviews you are given a not very complex algorithm based problem. Coding is done in an online editor without codecompletion. You have to tell the complexity of an algorithm. I was asked to think how to solve the same problem given a huge data input. I was asked some Java related questions (How hashmaps work, how does GC work) After that I promptly received an invitation for the onsite interviews (at Paris office). Criteo booked a flight and hotel 4 minutes away from the office. The onsite part consisted of 4 f2f interviews (with 1 or 2 employees) First 2 interviews were almost the same as Skype. You write code on whiteboard, discuss the complexity, improve the brute force solution, scale the solution for large inputs. 3rd interview was about system design. You have to discuss how you'd build the system to solve a given task, estimate the memory needed and how scale it. 4th interview is an informal talk with one of the senior tech managers, discussing your experience, interests and curiosity in technology. After 4 days I received an email describing each step of the process, telling how I performed and where I didn't do well. All in all I had a nice experience, everyone was friendly and no hidden catches in the progress. PS. you get a little present after the interview, also a nice gesture.