Amazon Non Software Development Engineer interview questions

Got an email saying I had to give 2 tech interviews of an hour each very next day. It said the tech will mainly be on data structure, algorithms and OOPS. First interviews was a woman who was really nice and friendly. Asked me about my resume first then told that I had to code a few questions she asked. 1) Design a Singleton Class 2) Write an least complex alto to find the first least appearing letter in a given string. 3)I don't remember this question. Second interviewer was straight to the point. As i picked up the phone he told me to open my email as he had sent a link to collabedit.com where I had to code. 1) Check whether two given binary trees are of identical(same depth and same values) 2) Given a log file which consists of timestamp, customer ID, page id visited by that particular customer. Write a function to return all customers who have visited 5 unique pages in last 30 mins.............And yes I dint get this code and entire interview got over in this question....... I got 4 out of 5 programs asked in 2 interviews, I was not expecting to get selected as Amazon has very high standards but one morning got an email saying Amazon is extending internship offer to me. Advice : Don't lose hope even if you don't know the exact code, let the interviewer know what thinking process is going on in ur brain. Big companies want people who can think. And give utmost importance to Data structure and Algorithms

applied online got an email saying they need me to give an online assessment test. The questions were pretty straight forward regarding linked lists and nodes.