HSBC Associate Financial Engineer interview questions

I went through 3 round of interview process in total. The very first round was talking with 3 colleagues in python as a language and mathematics probability problem. Second round is more of system design and programming in general. Last round with the manager in Guangzhou which is actually not very pleasant since the guy interviewing seems not very respectful for what I have said about my previous work. After all these, HR told me the salary is about 15% decrease which I can understand. But later on they changed their mind and said the boss is not happy about the number of the salary due to the level I was qualified in. And insist to remain 30% decrease which is totally unacceptable. The firm really has no integrity at all after the whole interview process.