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原题
Implement a trie with insert, search, and startsWith methods.
Example:
Trie trie = new Trie();
trie.insert(“apple”);
trie.search(“apple”); // returns true
trie.search(“app”); // returns false
trie.startsWith(“app”); // returns true
trie.insert(“app”);
trie.search(“app”); // returns true
Note:
You may assume that all inputs are consist of lowercase letters a-z.
All inputs are guaranteed to be non-empty strings.
解法
参考:
花花酱 LeetCode 208. Implement Trie (Prefix Tree)
AC Python Solution
定义TrieNode类, 它的孩子是字典, 字典的key是字母, value是TrieNode. 每个TrieNode的属性包含是否为单词.
代码
class TrieNode(object):
def __init__(self):
self.children = collections.defaultdict(TrieNode)
self.is_word = False
class Trie(object):
def __init__(self):
"""
Initialize your data structure here.
"""
self.root = TrieNode()
def insert(self, word):
"""
Inserts a word into the trie.
:type word: str
:rtype: void
"""
curr = self.root
for ch in word:
curr = curr.children[ch]
curr.is_word = True
def search(self, word):
"""
Returns if the word is in the trie.
:type word: str
:rtype: bool
"""
curr = self.root
for ch in word:
curr = curr.children.get(ch)
if curr is None:
return False
return curr.is_word
def startsWith(self, prefix):
"""
Returns if there is any word in the trie that starts with the given prefix.
:type prefix: str
:rtype: bool
"""
curr = self.root
for ch in prefix:
curr = curr.children.get(ch)
if curr is None:
return False
return True
# Your Trie object will be instantiated and called as such:
# obj = Trie()
# obj.insert(word)
# param_2 = obj.search(word)
# param_3 = obj.startsWith(prefix)
本文标签: implementLeetCodetriePythontree
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