Algorythma interview questions

After applying I was contacted for an interview. They were fairly inflexible with available time slots so scheduling the interview took a couple of weeks. The interview lasted one hour and revolved around questions covering machine learning and statistics/time series. Upon completing the interview I did not hear back from the hiring manager. After 3+ weeks of no contact I reached out to him and was told that "he thought" someone had already told me my application was rejected. When asked about giving some feedback as to why I was rejected/ what I could improve upon there was no reply. I personally find this a bit odd and lacking of common courtesy when a candidate has spent time interviewing. Overall, the interview process seems a bit unprofessional and unstructured but otherwise normal.

Face 2 Face interview. Lots of peaople are coming and waiting for whole day. Some java programs ,multithreading synchronization ,logic reasoning, pzzles. Interviewer is good and honest. After that hr round is there