We used Codepair in the interview. The problem is not hard, but I just forgot a point of C++ and got very nervous. I couldn't be able to understand the problem and when I finally understood and tried to write the code, time was up.

2 OAs which test in depth concepts of C++ and LC type questions with only one test case for each. After passing both OAs phone call for 30 minutes interview. Interviewer had an omniscient god like feeling despite being conceptually incorrect. I don't know why they take interviews when the interviewer won't even listen to you and they are gonna reject even if you code the solution. Don't waste your time.