I am trying to solve the below leetcode problem

Design a data structure that simulates an in-memory file system.

Implement the FileSystem class:

FileSystem() Initializes the object of the system. List ls(String path) If path is a file path, returns a list that only contains this file's name. If path is a directory path, returns the list of file and directory names in this directory. The answer should in lexicographic order. void mkdir(String path) Makes a new directory according to the given path. The given directory path does not exist. If the middle directories in the path do not exist, you should create them as well. void addContentToFile(String filePath, String content) If filePath does not exist, creates that file containing given content. If filePath already exists, appends the given content to original content. String readContentFromFile(String filePath) Returns the content in the file at filePath.

Example 1:

Input

["FileSystem", "ls", "mkdir", "addContentToFile", "ls", "readContentFromFile"]
[[], ["/"], ["/a/b/c"], ["/a/b/c/d", "hello"], ["/"], ["/a/b/c/d"]]

Output

[null, [], null, null, ["a"], "hello"]

Explanation

FileSystem fileSystem = new FileSystem();
fileSystem.ls("/");                         // return []
fileSystem.mkdir("/a/b/c");
fileSystem.addContentToFile("/a/b/c/d", "hello");
fileSystem.ls("/");                         // return ["a"]
fileSystem.readContentFromFile("/a/b/c/d"); // return "hello"

Below is the code I have written for it

class FileSystem:def __init__(self):self.root = {}def ls(self, path: str) -> List[str]:path = path.split('/')node = self.rootfor char in path:if char in node:node = node[char]print(node)node = list(node)print(node)print(path)return sorted(node)def mkdir(self, path: str) -> None:path = path.split('/')node = self.rootfor char in path:if char not in node:node[char] = {}node = node[char]def addContentToFile(self, filePath: str, content: str) -> None:node = self.rootfilePath = filePath.split('/')for char in filePath:if char not in node:node[char] = {}node = node[char]node[content] = '*'def readContentFromFile(self, filePath: str) -> str:node = self.rootfilePath = filePath.split('/')for char in filePath:if char not in node:return "Error"node = node[char]result_list = list(node.keys())return "".join(result_list)

Here is an input I am struggling with

["FileSystem","mkdir","ls","ls","mkdir","ls","ls","addContentToFile","ls","ls","ls"]
[[],["/goowmfn"],["/goowmfn"],["/"],["/z"],["/"],["/"],["/goowmfn/c","shetopcy"],["/z"],["/goowmfn/c"],["/goowmfn"]]

Here is the expected output:

[null,null,[],["goowmfn"],null,["goowmfn","z"],["goowmfn","z"],null,[],["c"],["c"]]

Here is my incorrect output

[null,null,[],["goowmfn"],null,["goowmfn","z"],["goowmfn","z"],null,[],["shetopcy"],["c"]]

I believe the issue comes in when I am not able to return the name of the file for a ls statement but instead return the content of the statement

How do I ensure that when the ls method is run I return the file name or contents in the path not the file contents?

Cheers!

The way you encode a file in the data structure makes it hard to distinguish it from a directory with the same name. Moreover, you define the content of the file as if it were a subdirectory of the "file". It will be easier to work with, if you define the file not as a dictionary, but as its own type (like the instance of a File class). That way it can be easily recognised and its content can be an attribute.

Here the code updated with that idea on encoding a file.

At the same time, I also:

• Subclassed FileSystem from dict, so it does not need a root attribute.

• Defined a separate method for walking down a path -- since that is what almost every other method must do, and so we avoid code repetition. Extra arguments to this method will determine whether missing directories should be created automatically, or an error should be thrown, and what the path is supposed to point at (a file, a directory, or either)

• Defined a class File with name and content.

class File:def __init__(self, name, content=""):self.name = nameself.content = contentclass FileSystem(dict):def walk(self, path: str, autocreate: bool=False, expected: str="any") -> Union['FileSystem', File]:if not path.startswith("/"):raise ValueError("Path should start with slash")path = path[1:]if path.endswith("/"):path = path[:-1]child = selfdirectories = path.split("/") if path else []path = ""for i, directory in enumerate(directories):path += "/" + directoryparent = childif not directory in parent:if not autocreate:raise ValueError(f"Invalid path: '{path}'")# auto create entryparent[directory] = File(directory) if i == len(directories) - 1 and expected == "file" else FileSystem()child = parent[directory]if expected != "any" and (expected == "file") != isinstance(child, File):raise ValueError(f"'{path}' is not a {expected}")return childdef ls(self, path: str) -> List[str]:node = self.walk(path)return sorted(node) if isinstance(node, FileSystem) else [node.name]def mkdir(self, path: str) -> None:self.walk(path, True, "directory")def addContentToFile(self, filePath: str, content: str) -> None:self.walk(filePath, True, "file").content += contentdef readContentFromFile(self, filePath: str) -> str:return self.walk(filePath, False, "file").content