A phone interview where I was asked data structure questions: what is hash table, what is binary search tree, why would you use one over the other. Same goes for linked list and array. And run times of find_element() for these data structures. I got invited for an on-site interview at their headquarter. It consisted of three 30-min coding interviews. The people there are very relaxed and friendly. I did not get an offer, but they notified my really soon and encouraged me to reapply.