Leetcode 114：Flatten Binary Tree to Linked List

Given a binary tree, flatten it to a linked list in-place.For example, given the following tree:The flattened tree should look like:这道题要求把二叉树展开成链表根据展开后形成的链表的顺序分析出是使用先序遍历。想到树的遍历立马会联想到递归的方法。不过也不是一定要递归啦这里用递归和非递归的两种方法来解决。C void flatten(TreeNode* root) { if(root nullptr) return; if(root-left)flatten(root-left); if(root-right)flatten(root-right); TreeNode* temp root-right; root-right root-left; root-left nullptr; while(root-right)root root-right; root-right temp; }下面这个是非递归的方法C void flatten(TreeNode* root) { //非递归方法 TreeNode* cur root; while(cur) { if(cur-left) { TreeNode* p cur -left; while(p-right)p p-right; p-right cur-right; cur-right cur-left; cur-left nullptr; } cur cur-right; } }