Intuitive Graphics Software Engineer interview questions

The hiring manager called and talked to me and said that they are going to set up an all-day interview but it might take a while. Then, they set up an all-day interview session three business days after the initial call. The hiring manager send me some topics to read about but the topics covered most of C++, multithreading, and CUDA domain (which is a lot to cover in three days!!). I presented for an hour in the morning, they asked questions and I answered them. In the afternoon, the individual interviews started. The first interviewer didn't know what the hiring manager wanted for this position and asked some irrelevant questions. The next interviewer was the hiring manager himself. Asked a couple of questions and told me to do some coding. At the end of the session, he said thank you for presenting and good luck with the rest of the interviews. The next interviewer never showed up and I got an email a couple of minutes later that the rest of the interviews are canceled. This is the worst interview experience I've had so far! Never will interview for this company again. Unprofessional and insensitive to other people's time.