Google Software Development Engineer interview questions

A recruiter from Google's college recruiting team contacted me after my friend referred me. The process was very fast. I had a phone interview with an engineer from Google's NYC office two weeks later. It was a standard 45-minute technical interview. The interviewer started the interview with a coding problem directly. BTW, we used Google docs as the white board. I finished the first coding problem with two solutions and he verified both of them. But we didn't leave much time for the second problem, I wrote down some code and the time was up. One week later, I got the onsite invitation. The onsite interview included four sessions. All of them were technical interviews. Almost two weeks after the onsite interviews, I got a call from my recruiter, she gave a bad news :(