1 phone interview, 4 onsite interviews in total. During the phone interview, they mainly focused on my past working experience and basic technical skills, also I was asked with an open question, to describe how to make use of user event data (such as page view, ad click, search) to target the user to the most relevant ad. During the onsite interviews, they mainly focused on coding skills, problem solving as well as logical thinking. I was asked to write a function for string edit distance in C/C++, there was also a probability problem .