Amazon VO 面试真题解析：可扩展的文件搜索库设计

The Unix find command allows you to search for files under a given directory. You can specify criteria for files you are interested in.

Imagine that you need to write code in a high-level language like Java that does things similar to the find command. I would like you to focus on two use cases at first:

• Find all files over 5 MB somewhere under a directory.
• Find all XML files somewhere under a directory.

I would like you to create a library that lets me do this easily. Keep in mind that these are just two use cases, and that the library should be flexible.

这道题考察的是如何设计一个可扩展的文件搜索库，核心思路不是把两个需求写死，而是抽象出统一的筛选接口，让路径遍历与条件判断解耦。可以用递归或栈遍历目录树，再配合组合式过滤器来表达“大小大于 5MB”“后缀是 XML”等规则；如果要支持更多条件，还可以把多个谓词按 AND/OR 组合，保持 API 灵活。面试时重点应说明如何定义文件元信息、如何组织搜索条件，以及如何让新增规则不修改已有逻辑。