Sabre Senior Operations Research Analyst interview questions

I got the interview for Senior Operations Research Analyst. There were two rounds of phone interview. The first interview is about Operations Research questions, eg decompostion method, how dose column generation work. The second interview is about programming in c++, mostly object-oriented part. They are require experience with class, version control and etc.

I applied Sr. operation research analyst position via online (sabre webpage). They called me back 2 month later and we had three phone interviews. Interview questions were quite difficult. They asked many high level C++ questions and I could not answer correctly.