My first round/ screening round was on skype. He asks my brief introduction which was a formality and I finished that within 2 minutes.Thereafter he asked questions on string and told me to explain first approach then write the code. I explained him hashing/sorting approach with its pros/cons and wrote the code in c++.He wanted production ready code i.e. all test cases should be handled properly. After that few follow up questions and ended the interview.