[leetcode] implement trie

class :
    def __init__(self):
        self.is_word = False
        self.chars = {}

class Trie:

    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.root = TrieNode()

    def insert(self, word):
        """
        Inserts a word into the trie.
        :type word: str
        :rtype: void
        """
        node = self.root
        for w in word:
            if w not in node.chars:
                node.chars[w] = TrieNode()
            node = node.chars[w]
        node.is_word = True


    def search(self, word):
        """
        Returns if the word is in the trie.
        :type word: str
        :rtype: bool
        """
        node = self.root
        for w in word:
            if w not in node.chars:
                return False
            node = node.chars[w]
        return node.is_word


    def startsWith(self, prefix):
        """
        Returns if there is any word in the trie that starts with the given prefix.
        :type prefix: str
        :rtype: bool
        """
        node = self.root
        for w in prefix:
            if w not in node.chars:
                return False
            node = node.chars[w]
        return True



# obj = Trie()
# obj.insert(word)
# param_2 = obj.search(word)
# param_3 = obj.startsWith(prefix)