Implement x to the power of n without using any built-in library.

"The process was first a phone screen followed by a virtual loop with four rounds. The phone screen was a single tree traversal coding problem, and the onsite had two coding rounds, one system design round, and one behavioral round. The most interesting part was a new AI coding section that I hadn't seen before. It sounded new enough that even the format felt a little flexible, but the expectation was still that I do the actual coding myself and only use AI in a limited way. Overall it was pretty challenging, and if I did it again I would spend more time on behavioral prep because that was my weakest part."