Recruiter that I had met previously extended an email asking if I wanted to apply for the position. I said yes, and they gave me an online coding challenge. Don't really remember the coding challenge question but it was regarding a network of users, and how to store them and check if they are related. I solved it using a HashMap. Next question was how to deal with a large increase in scale. I said parallelize the HashMap and put parts of the network on different machines. They said they were impressed with my coding challenge and offered a phone interview. Over the phone they asked me given a network of friends like Facebook, describe a function that would tell whether two people were mutual friends. I solved using DFS. They didn't ask me about time or space complexity which I thought was weird, they said I solved the question and there was nothing else they needed to hear. A few days later they said they didn't want to move on without any reason why.