Trie树的操作

Trie树的操作：插入、搜索

class TrieNode():
    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.child = {}
        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
        """
        node = self.root
        for letter in word:
            data = node.child.get(letter)

            if data is None:
                node.child[letter] = TrieNode()

            node = node.child[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.child.get(letter)
            if not node:
                return False           
        return node.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
        """
        node = self.root
        for letter in prefix:
            node = node.child.get(letter)
            if not node:
                return False
        return True

    def get_start(self, prefix):
        """
        Returns words started with prefix
        :param prefix:
        :return: words (list)
        """

        #递归求出pre_node之后的child，其中pre是前面所有的字符串，pre_node是前一个trienode
        def _get_key(pre,pre_node):
            words_list = []
            if pre_node.is_word:
                words_list.append(pre)
            for x in pre_node.child.keys():
                words_list.extend(_get_key(pre+str(x), pre_node.child.get(x)))
            return words_list

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


trie = Trie()
trie.insert("startswith")
trie.insert("somebody")
trie.insert("somebody1")
trie.insert("somebody3")
print(trie.search("key"))
print(trie.search("somebody3"))
print(trie.get_start('some'))  
# t = TrieNode() 
# t.child['some'] = 1
# print(t)