bool search(std::string word) 
	{
		TrieNode* current = root, *node = nullptr;
		for (int i = 0; i < word.size(); ++i)
		{
			node = current->getSon(word[i]);//查找当前字符对应的子节点是否存在
			if (node == nullptr)
				return false;
			current = node;
		}
		return node->isEnd(); //注意这里,就算所有字符都存在,也要看是不是一个字符串的结尾
	}
	bool startsWith(std::string prefix) 
	{
		TrieNode* current = root, *node = nullptr;
		for (int i = 0; i < prefix.size(); ++i)
		{
			node = current->getSon(prefix[i]);
			if (node == nullptr)
				return false;
			current = node;
		}
		return true;
	}
	void insert(std::string word) 
	{
		TrieNode* current = root, *node = nullptr;
		for (int i = 0; i < word.size(); ++i)
		{
			node = current->getSon(word[i]);
			if (node == nullptr)//该字符对应的子节点不存在,就创建一个子节点,连接到该字符
			{
				node = new TrieNode();
				current->setSon(word[i], node);
			}
			current = node; //current指向子节点
		}

		node->setEnd(); //插入完一个字符串之后,setEnd表示字符串结束
	}