Applied online - got an HR screen a week later. Cleared it easily - just simple OOPS concepts and a couple of time complexity questions. Nothing out of the ordinary . Next comes the technical phone screen, with coderpad. Not very friendly I must admit, she just asked if I had it open , after saying hello, and she asked me to find duplicates in a list. Simple enough, I gave her 3 solutions, in O(n^2), O(nlogn) and O(n), with clear explanation as to how I arrived at the time complexity. Next, she said what if I had 50 trillion data entries - immutable and no additional data structures . I thought and said I'd hash it, use a multiset, and fumbled around a bit. Cost me the entire interview. But I kept asking her more details, gave her a couple of explanations about the hashcode method , overriding it, using XOR - all the stuff I could think of. Got a reject a day later. Sigh.