Google Software Engineer - Internship interview questions

3 phone interviews, Recruiter remains in contact, the First interviewer asked a difficult question on DFS. next was supposed to be a back to back interview but it was postponed to two weeks later. got selected for the final coding round. The interview went very well and I answered all the questions. But at last they rejected me

It was a pretty interesting process, I didn't belive how much time it took them to get back to me since I had applied and then over a few months later they came back and said that it was going to take more time but then eventually it was done and I ahd tht interview and it was aite