LeetCode----Add and Search Word - Data structure design

Add and Search Word - Data structure design

Design a data structure that supports the following two operations:

void addWord(word)
bool search(word)

search(word) can search a literal word or a regular expression string containing only letters 

a-z

 or 

.

.
A 

.

 means it can represent any one letter.

For example:

addWord("bad")
addWord("dad")
addWord("mad")
search("pad") -> false
search("bad") -> true
search(".ad") -> true
search("b..") -> true

Note:

You may assume that all words are consist of lowercase letters 

a-z

.

click to show hint.

You should be familiar with how a Trie works. If not, please work on this problem: Implement Trie (Prefix Tree) first.

分析：

同上一题，实现Trie树。增加了“.”的支持。使用递归完成。

代码：

class TrieNode(object):
def __init__(self):
"""
Initialize your data structure here.
"""
self.tnlst = {}
self.terminal = False

def __str__(self):
return str(self.tnlst.items())

class WordDictionary(object):
def __init__(self):
"""
initialize your data structure here.
"""
self.root = TrieNode()

def addWord(self, word):
"""
Adds a word into the data structure.
:type word: str
:rtype: void
"""
r = self.root
for w in word:
if w not in r.tnlst:
r.tnlst[w] = TrieNode()
r = r.tnlst[w]
r.terminal = True

def search(self, word):
"""
Returns if the word is in the data structure. A word could
contain the dot character '.' to represent any one letter.
:type word: str
:rtype: bool
"""
return self.searchLeaf(self.root, word)

def searchLeaf(self, curNode, word):
if not word:
if not curNode.terminal:
return False
return True
ch = word[0]
if ch == '.':
for i in curNode.tnlst.keys():
if self.searchLeaf(curNode.tnlst[i], word[1:]):
return True
return False
if ch in curNode.tnlst:
return self.searchLeaf(curNode.tnlst[ch], word[1:])
else:
return False