摘要：
There are three types of depth-first traversal: pre-order,in-order, and post-order.For a binary tree, they are defined as operations recursively at ea... 阅读全文
摘要：
一、判断链表是否存在环，办法为：设置两个指针(fast, slow)，初始值都指向头，slow每次前进一步，fast每次前进二步，如果链表存在环，则fast必定先进入环，而slow后进入环，两个指针必定相遇。二、找到环的入口点当fast若与slow相遇时，slow肯定没有走遍历完链表，而fast已经... 阅读全文