Meta Software Developer interview questions

First stage involved 2-Phone Interviews with coding using collabedit like software. Couple of days later, offered on-site. Given option to fly out to Menlo Park the very next day, or interview over skype. Chose latter due to time constraints. The first interviewer (second stage), after going over experience asked to come up with a design of a simple web-based editor (like collabedit), and questions about basic tree manipulation followed (since dom was represented as tree). First interview ran long, hence late to the second one. Was asked to quickly implement a solution to the N-queens problem for the second interview. Couldn't finish answering before time ran out.