Amadeus interview question

Coding: 1) Find the unique non-repeating element in the given array. (Hint: use XOR operator for O(n)) 2) The second question was a long one but it wasn't too difficult. It was definitely to test the candidate's understanding of a lengthy problem and come up with an optimal soln. Interview: Basics from Java, DBMS, OOPS, Networking, DSA, OS and be prepared with whatever you have written in your Resume (I was quizzed on almost all the skills I had mentioned in my resume). The interview was conducted on HackerEarth whiteboard so there is a live compiler present where I was asked to implement Linked List data structure (not the collections) and run time polymorphism. HR interview was basic questions like tell me about yourself, why do you want to join Amadeus, issues regarding relocation, etc.