LinkedIn Sr. Software Engineer interview questions

The company recruiter found my profile on LinkedIn and had a brief interview. Then we scheduled an technical interview with a developer, questions were not difficult. After that I went on-site for a one round of group interview, and then went for second round on-site with 4 consecutive group interviews.

I got an email within a week after I applied to set up a phone interview with one of the engineers. The interview started off with the interviewer asking me to implement an iterator,LRU Cache and a doubly linked list in java in Collabedit . I thought I did pretty decently given the one hour time frame, however I got an email back saying that they would like to interview me again because they thought I could do better !!. Anyway second collabedit interview general java questions and some tricky collections coding questions later,they sent an email to offer there regrets...