python实现字典树

#定义一个字典树节点的类
class TrieNode(object):
    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.data = {}
        self.is_word = False

#字典树
class Trie(object):

    def __init__(self):
        self.root = TrieNode()

    def insert(self, word):
        """
        Inserts a word into the trie.
        :type word: str
        :rtype: void
        """
        node = self.root
        for letter in word:
            child = node.data.get(letter)
            if not child:
                node.data[letter] = TrieNode()
            node = node.data[letter]
        node.is_word = True

    def search(self, word):
        """
        Returns if the word is in the trie.
        :type word: str
        :rtype: bool
        """
        node = self.root
        for letter in word:
            node = node.data.get(letter)
            if not node:
                return False
        return node.is_word  # 判断单词是否是完整的存在在trie树中

    def starts_with(self, prefix):
        """
        Returns if there is any word in the trie
        that starts with the given prefix.
        :type prefix: str
        :rtype: bool
        """
        node = self.root
        for letter in prefix:
            node = node.data.get(letter)
            if not node:
                return False
        return True

    def get_start(self, prefix):
        """
        Returns words started with prefix
        :param prefix:
        :return: words (list)
        """
        #利用到了递归
        def _get_key(pre, pre_node):
            words_list = []
            if pre_node.is_word:
                words_list.append(pre)
            for x in pre_node.data.keys():
                words_list.extend(_get_key(pre + str(x), pre_node.data.get(x)))
            return words_list

        words = []
        if not self.starts_with(prefix):
            return words
        # if self.search(prefix):
        #     words.append(prefix)
        #     return words
        node = self.root
        for letter in prefix:
            node = node.data.get(letter)
        return _get_key(prefix, node)


# Your Trie object will be instantiated and called as such:
trie = Trie()
trie.insert("somestring")
trie.insert("somebody")
trie.insert("some")
trie.insert("somebody1")
trie.insert("somebody3")
print(trie.search("key"))
print(trie.search("somebody3"))
print(trie.get_start('some'))

###########################################结果

False
True
['some', 'somestring', 'somebody', 'somebody1', 'somebody3']