1 class TrieNode:
 2     def __init__(self):
 3         self.words = 0
 4         self.edges = [None] * 26
 5 
 6 
 7 class WordDictionary:
 8     def __init__(self):
 9         self.root = TrieNode()
10 
11     def addWord(self, word: str) -> None:
12         self.insertHelper(self.root,word,0)
13 
14     def search(self, word: str) -> bool:
15         return self.searchHelper(self.root,word,0) != 0
16 
17     def insertHelper(self,node,word,pos):
18         if pos == len(word):
19             node.words += 1
20         else:
21             char_code = ord(word[pos]) - 97
22             if node.edges[char_code] == None:
23                 node.edges[char_code] = TrieNode()
24             self.insertHelper(node.edges[char_code],word,pos+1)
25 
26 
27     def searchHelper(self,node,word,pos):
28         if pos == len(word):
29             return node.words
30         else:
31             if word[pos] == '.':#任意字符的判断
32                 for i in range(26):
33                     if node.edges[i] != None:
34                         res = self.searchHelper(node.edges[i],word,pos+1)
35                         if res != 0:
36                             return res
37                 return 0
38             else:#具体字母的判断
39                 char_code = ord(word[pos]) - 97
40                 if node.edges[char_code] == None:
41                     return 0
42                 else:
43                     return self.searchHelper(node.edges[char_code],word,pos+1)

算法思路：前序树Trie。

根据 leetcode208 Implement Trie (Prefix Tree)，改造出来的。