Amazon Software Development Engineer interview questions

Applied online and heard from a recruiter within 3 hours. They had an upcoming interviewing drive. The recruiter discussed with me the position in the Toronto office on the phone to asses my suitability. Afterwards I was invited for an in-person technical interview for the following week. The interview included four 1-on-1 sessions. Three of which were technical, one of which was more traditional HR (with the group's hiring manager). The first technical interview was the standard stuff about binary search trees and hashing. The second one (bar raiser) had a question about path finding in a grid-maze with obstacles. Third interview had some questions regarding string manipulation in C and finding pairs that sum to k in an unsorted integer array.