Attended this interview through recruiter. They scheduled first round with one of other tech lead. In this round, they asked to complete system design within 30 mins, it end up with 45 mins. Then coding round , question was very easy one. Since I well at collections. I went with list with O(1) time complexity. But still rejected. May be interviewer wanted me to solve this coding in stack rather than list. My Interviewer seems act like invigilator, not in collaborative mode. In this case google interviewers are amazing.