Amazon Developer interview questions

Phone interview: 1. Write a function that determines if a given string is a palindrom 2. Asked about virtual functions, in detail. Assume there exist a c_bird class, penguen inherits from it, flapWing method exist in both classes, if defined virtual or not, whichever one is called when. 3. Detect loop in a linked list. When I gave a solution with two pointers, he followed up saying if you are not allowed to use two pointers, but have access to number of elements in the linked list, how do you do. 4. Implement priority queue with enqueue and dequeue methods, make it as flexible as possible.