Amazon Software Development Engineer interview questions

A recruiter contacted me after seeing my profile on linkedin. After a screening phone interview with the recruiter they set-up a 75-minute technical phone interview with one of their SDEs. They set-up a collabnet session where you had to write code on-the-fly. After a brief discussion about my work history, he asked 3 questions: 1. tell me what you know about binary search trees. 2. write method which takes a tree node and returns true/false if it is a bst. 3. write a method which takes an array of ints and an int value, and return all pairs of values from the array that add up to the value. All 3 should have been easy questions, but I badly flubbed #2 and #3 :-) Dumb, because I had seen both of those questions posted here and on other sites.