高频题（0）
1. Design a Web Crawler System
Design a web crawler system. Explain how you would scale the system and reduce resource usage.
2. Implement a BufferedFile Class
Given a File class, implement a BufferedFile to simulate a file writer with a buffer. As a follow-up, discuss how you would optimize the buffer.
3. Implement a File System API
Given a file system API, implement an API to list and delete all files under a given path. Additionally, as a follow-up, describe how you would reduce resource usage.
