In-Memory File System

class TrieNode:
    def __init__(self):
        self.next = {}
        self.word = ''

class FileSystem(object):

    def __init__(self):
        self.root = TrieNode()
        
    def insert(self, path):
        trie_crawl = self.root
        for i in path.split('/')[1:]:
            if not i in trie_crawl.next:
                trie_crawl.next[i] = TrieNode()
            trie_crawl = trie_crawl.next[i]
            
        return trie_crawl
    
    def search(self, path):
        trie_crawl = self.root
        for i in path.split('/')[1:]:
            if not i in trie_crawl.next:
                return trie_crawl
            trie_crawl = trie_crawl.next[i]
            
        return trie_crawl 
        

    def ls(self, path):
        """
        :type path: str
        :rtype: List[str]
        """
        temp_list = [path.split('/')[-1]]
        trie_c = self.search(path)
        if trie_c.word:
            return temp_list
        
        temp_list = sorted(trie_c.next.keys())
        
        return temp_list
        

    def mkdir(self, path):
        """
        :type path: str
        :rtype: None
        """
        self.insert(path)
        

    def addContentToFile(self, filePath, content):
        """
        :type filePath: str
        :type content: str
        :rtype: None
        """
        trie_c = self.insert(filePath)
        trie_c.word += content
        

    def readContentFromFile(self, filePath):
        """
        :type filePath: str
        :rtype: str
        """
        trie_c = self.search(filePath)
        return trie_c.word
        


# Your FileSystem object will be instantiated and called as such:
# obj = FileSystem()
# param_1 = obj.ls(path)
# obj.mkdir(path)
# obj.addContentToFile(filePath,content)
# param_4 = obj.readContentFromFile(filePath)