Bloomberg Software Engineer interview questions

No screening straight into an hour technical interview. Was asked no cultural questions and was given a very hard problem. The interviews called on the phone and had a Russian accent so understanding him was already difficult. As I was thinking out loud he told me just start writing code. He also mentioned he wanted running code specifically. I go through my code and I have to write my own class and main method to test btw. After I test I realized I had a fundamental misunderstanding of the problem and the interviewer never mentioned anything to me the entire time. He gave 0 hints of help of any kind.