标签：
Given a binary tree, flatten it to a linked list in-place.
For example,
Given
1
/ 2 5
/ \ 3 4 6
The flattened tree should look like:
1
2
3
4
5
6
If you notice carefully in the flattened tree, each node‘s right child points to the next node of a pre-order traversal.
分析：
使用递归，存储原始树的左子树。需要注意的是题目要求in-place,因此不能用new TreeNode(X)构造新节点并作为结果返回。
代码如下：
1 class TreeNode { 2 int val; 3 TreeNode left; 4 TreeNode right; 5 TreeNode(int x) { val = x; } 6 } 7 8 public class Solution { 9 public void flatten(TreeNode root) { 10 if(root != null) { 11 TreeNode left = root.left; 12 TreeNode right = root.right; 13 14 root.left = null; 15 root.right = left; 16 flatten(root.right); 17 18 while(root.right != null) { 19 root = root.right; 20 } 21 22 root.right = right; 23 flatten(root.right); 24 } 26 } 27 }
LeetCode-114 Flatten Binary Tree to Linked List
标签：
原文地址：http://www.cnblogs.com/linxiong/p/4215919.html
