[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