Keep Only Folders Without a Listed Ancestor

### Problem Given unique valid absolute folder paths, remove every path that is a subfolder of another listed path. A path is a subfolder only when the ancestor path is followed immediately by a slash and then more path text. Return all surviving paths in any order. ```cpp class Solution { public: vector<string> removeSubfolders(vector<string>& folder); }; ``` ### Examples **Example 1:** ```text Input: folder = ["/q/r","/q","/qr","/z"] Output: ["/q","/qr","/z"] Explanation: /q/r is inside /q, while /qr is a different top-level name. ``` **Example 2:** ```text Input: folder = ["/m/n","/m/n/o","/m/p"] Output: ["/m/n","/m/p"] Explanation: Only /m/n/o has another listed path as an ancestor. ``` ### Constraints - There are 1 to 40000 unique folder paths. - Every path has length 2 to 100, starts with `/`, and uses lowercase English letters and slashes. - Paths follow the stated nonempty-segment format. ### Contract considerations Each path consists of one or more nonempty lowercase segments prefixed by slashes; `/` alone is not a valid path. ```hint Read the boundary condition Does a shared character prefix alone make one path a subfolder, or must a slash mark the ancestor boundary? ``` ### What a Strong Answer Covers Each path consists of one or more nonempty lowercase segments prefixed by slashes; `/` alone is not a valid path. ### Follow-up Questions Optional practice extension, separate from the original task: How could paths be processed incrementally rather than all at once?