Excellent interview process, I went thru 3 rounds. The type of knowledge they want is pretty impressive. Basically more on analytical process and yes code complexity was the main focus. I have never been interviewed in such a way and never been asked about code complexity. Not sure if I am selected or not but I can say I liked the interview process. Very systematic and very nicely done. I enjoyed it thoroughly. The company looks great, I guess no restrictions on your attire. What you feel is good for you, you can wear it. Cool culture, cool environment. No wonder Amazon has taken over it. Look forward to work with them, if I get chance.