Problem: Hierarchical Folder Access Check

You are tasked with simulating a simple hierarchical file system and implementing an access-check function. The file system consists of folders arranged in a tree structure.

Access rules are as follows:

• A user is granted direct access to a specific subset of folders.
• Access is inherited down the tree: if a user has access to a parent folder, they automatically have access to all of its descendant folders.

You will be provided with the following inputs:

• allFolders: A list of all folders in the system, represented as absolute paths from the root (e.g., "/", "/A", "/A/B/C").
• accessibleFolders: A set of folder paths to which the user has direct access (e.g., {" /A", "/F"}).

Function to Implement

You need to implement the function:

bool HasAccess(string folderPath)

This function should return:

• true if the user has access to folderPath either because:
  • folderPath itself is present in accessibleFolders, OR
  • An ancestor folder of folderPath (e.g., /A is an ancestor of /A/B/C) is present in accessibleFolders.
• false otherwise.

Assumptions

• All folder paths in allFolders and accessibleFolders are normalized absolute paths, starting with '/', with components separated by '/' (e.g., /A/B/C).
• folderPath passed into HasAccess is always a valid folder path present in allFolders.

Efficiency Requirement

Design and implement HasAccess so that it can be called many times efficiently after the initial inputs (allFolders and accessibleFolders) are known.

Examples

Given the following folder tree:

/
├── A
│   ├── B
│   │   ├── C
│   │   └── D
│   └── E
└── F

And accessibleFolders = {"/A", "/F"}:

• HasAccess("/A") → true (direct access)
• HasAccess("/A/B") → true (inherits from /A)
• HasAccess("/A/B/C") → true (inherits from /A)
• HasAccess("/A/E") → true (inherits from /A)
• HasAccess("/F") → true (direct access)
• HasAccess("/") → false (no access to root unless / is in accessibleFolders)