I had an initial phone screening where I was told about company culture and answered some questions about my experience. This was followed up with a technical interview a couple days later. It was set up as a video interview, which I wasn't aware of. I also didn't know there would be a coding challenge. The questions/conversation part went fine. The coding challenge didn't go as well. I was asked to write a function implementing a concept I wasn't familiar with. This part of the interview was maybe 30 minutes long, which included explaining the concept, me asking questions to try to understand what it was supposed to do/how it would work, and the actual implementation. I didn't get to a solution within the half hour. Afterward, I worked a couple extra minutes trying to figure out out before returning to work. I ended up looking up the solution and realized I wasn't really understanding what was being asked. I don't really feel generating the extra pressure of having candidates do a surprise monitored coding challenge with little time to implement is going to bring out the best in them to provide a fair assessment of their problem solving skills.