208_Implement_Trie_(Prefix_Tree).py

class TrieNode:
    def __init__(self):
        self.flag = False
        self.children = {}


class Trie(object):

    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: None
        """
        current = self.root
        for character in word:
            if character not in current.children:
                current.children[character] = TrieNode()
            current = current.children[character]
        current.flag = True


    def search(self, word):
        """
        Returns if the word is in the trie.
        :type word: str
        :rtype: bool
        """
        result, node = self.childSearch(word)
        if result:
            return node.flag
        return False

    def startsWith(self, prefix):
        """
        Returns if there is any word in the trie that starts with the given prefix.
        :type prefix: str
        :rtype: bool
        """
        result, node = self.childSearch(prefix)
        return result

    def childSearch(self, word):
        current = self.root
        for character in word:
            if character in current.children:
                current = current.children[character]
            else:
                return False, None
        return True, current


# Your Trie object will be instantiated and called as such:
# obj = Trie()
# obj.insert(word)
# param_2 = obj.search(word)
# param_3 = obj.startsWith(prefix)