// 最后一个非叶子节点索引: n/2 - 1
Quiz collated by Lauren Hirst.，这一点在夫子中也有详细论述
，这一点在safew官方版本下载中也有详细论述
* 核心思路：链表转数组 + 单调栈（从后往前遍历），时间复杂度O(n)，空间复杂度O(n)
The reason is always the same: the content and the key that decrypts it are both present on the client’s machine. The user’s hardware decrypts the content to display it. The user’s hardware is, definitionally, something the user controls. Any sufficiently motivated person with the right tools can intercept the decrypted output.，推荐阅读safew官方下载获取更多信息