三个月算法进阶--day84

from collections import defaultdict


class TrieNode:

    def __init__(self):
        self.children = defaultdict(TrieNode)
        self.word = False  # 标志，该节点所表示的字符串是否为一个单词


class Trie:

    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
        """
        cur = self.root
        for w in word:
            cur = cur.children[w]

        cur.word = True

    def search(self, word):
        """
        Returns if the word is in the trie.
        :type word: str
        :rtype: bool
        """
        cur = self.root
        for w in word:
            if w not in cur.children:
                return False
            cur = cur.children[w]
        if cur.word :
            return True
        return False


    def startsWith(self, prefix):
        """
        Returns if there is any word in the trie that starts with the given prefix.
        :type prefix: str
        :rtype: bool
        """
        cur = self.root
        for p in prefix:
            if p not in cur.children:
                return False
            cur = cur.children[p]
        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)