Implement a method to convert an integer to a string of bytes without using built-in helper functions.

"I went through a pretty long Microsoft process for an SDE II role compared with other companies. It started with a HackerRank, then a one-hour recruiter screen that was very focused on motivation and culture fit, and then a loop of three back-to-back interviews on coding, system design, and low-level design. What stood out to me was how vague several prompts were, because I had to keep asking questions to uncover the requirements instead of just jumping into a textbook answer. In the coding round, they seemed to care more about how I reasoned through the binary tree problem than whether I used the exact BFS or DFS terminology. Overall, it felt about the same difficulty as Google or Amazon, but a little more focused on logical thinking and culture."