208. Implement Trie (Prefix Tree)

implement a trie with insert, search, and startsWith methods.

Note:
You may assume that all inputs are consist of lowercase letters a-z.

 

 1 class Trie:
 2 
 3     def __init__(self):
 4         """
 5         Initialize your data structure here.
 6         """
 7         self.end = False
 8         self.c = {}
 9         
10 
11     def insert(self, word):
12         """
13         Inserts a word into the trie.
14         :type word: str
15         :rtype: void
16         """
17         node = self
18         for w in word:
19             if w not in node.c:
20                 node.c[w] = Trie()
21             node = node.c[w]
22         node.end = True
23                 
24         
25     def prefixnode(self, word):
26         node = self
27         for w in word:
28             if w not in node.c:
29                 return None
30             node = node.c[w]
31         return node
32     def search(self, word):
33         """
34         Returns if the word is in the trie.
35         :type word: str
36         :rtype: bool
37         """
38         node = self.prefixnode(word)
39         if not node:
40             return False
41         else:
42             if node.end:
43                 return True
44             else:
45                 return False
46 
47     def startsWith(self, prefix):
48         """
49         Returns if there is any word in the trie that starts with the given prefix.
50         :type prefix: str
51         :rtype: bool
52         """
53         node = self.prefixnode(prefix)
54         return node is not None
55         
56 
57 
58 # Your Trie object will be instantiated and called as such:
59 # obj = Trie()
60 # obj.insert(word)
61 # param_2 = obj.search(word)
62 # param_3 = obj.startsWith(prefix)

 

posted @ 2018-04-16 11:13  乐乐章  阅读(113)  评论(0)  编辑  收藏  举报