Apple Software Engineer interview questions

Initial call with a recruiter .Set up a phone screen the very next day. Had a techinical phone interview with code sharing .Given a BST print the nodes at each level on a seperate Line. I could do this easily with a queue ..but he wanted some thing with O(n) time complexity and O(1) space .ie no additional data structure like queues and linkedlists and array lists

On site interview from 10 AM to 5 PM. In total there were about 6 interviews for an hour each, and an hour lunch at 1 infinite loop. Interviewers were very fair and had a conversational demeanor. Apple paid to fly me out to CA and covered all of my expenses.