[leetcode trie]208. Implement Trie (Prefix Tree)

实现一个字典树

class Trie(object):

    def __init__(self):
        self.root = TrieNode()

    def insert(self, word):
        cur = self.root
        for i in word:
            cur = cur.children[i]
        cur.is_word = True
        

    def search(self, word):
        cur = self.root
        for i in word:
            cur = cur.children.get(i)
            if cur is None:
                return False
        return cur.is_word

    def startsWith(self, prefix):
        cur = self.root
        for i in prefix:
            cur = cur.children.get(i)
            if cur is None:
                return False
        return True
        
class TrieNode(object):
    def __init__(self):
        self.children = collections.defaultdict(TrieNode)
        self.is_word = False