Implement a hierarchical file store

Problem Statement

Design a memory-resident hierarchical file system. The system should support basic file operations using absolute and relative paths.

Implement the following interface:

• mkdir(path: str): Creates a new directory at the specified path. Returns True if successful, False if a file already exists at that location or the parent path does not exist.
• touch(path: str, content: str): Creates a file at the specified path with the given content. If the file exists, overwrite the content.
• read(path: str): Returns the content of the file. If the path does not exist or refers to a directory, return an error indicator (e.g., None).
• ls(path: str): Lists the contents of a directory. Return a sorted list of names. If path is a file, return a list containing only that filename.
• rm(path: str): Deletes the file or directory. If it is a directory, remove all its descendants.

Constraints

• Paths are strings like /home/user/docs/file.txt.
• You must handle the root directory /.
• Assume path components contain alphanumeric characters only.

Examples

fs = FileSystem()
fs.mkdir("/data")
fs.touch("/data/notes.txt", "hello world")
print(fs.ls("/data")) # Output: ["notes.txt"]
print(fs.read("/data/notes.txt")) # Output: "hello world"

Edge Cases

• Creating a file in a non-existent directory.
• Deleting the root directory.
• Repeated path separators (e.g., //home///user).