LinkedIn Software Engineer interview questions

The recruiter contacted me through email and arranged me a technical phone interview. I'm a little disappointed though, the interview was scheduled at 6:00PM Eastern Time. During the phone interview(using collabedit.com), the interviewer asked two coding questions: (1) the deepest common ancestor of two nodes of a tree (2) all permutations of a string. The questions were reasonable, but I failed to solve the second one. Also the interviewer thought I'm not engaging enough(didn't talk much).

I was contacted by a recruiter on LinkedIn, who later called me and informally discussed the position they were looking for and asked about my background. After this phone call, the recruiter scheduled an hour-long technical phone interview with two software engineers based on my availability, which happened to be 2 weeks after this initial phone call from the recruiter. The technical phone screen was conducted using collabedit. First, the interviewer asked about my background and what my favorite project was that I had worked on. Then, the technical questions began. He said, depending on the time, that 2 coding questions would be asked and we had enough time for both questions plus extra time for me to ask them questions. I coded my answers in C++. I was notified 3 days after the phone screen that they would not be moving forward with me.