二叉树的下一个节点

 1 /*
 2 public class TreeLinkNode {
 3     int val;
 4     TreeLinkNode left = null;
 5     TreeLinkNode right = null;
 6     TreeLinkNode next = null;
 7 
 8     TreeLinkNode(int val) {
 9         this.val = val;
10     }
11 }
12 */
13 public class Solution {
14     public TreeLinkNode first(TreeLinkNode p) {
15         if (p.left != null) {
16             return first(p.left);
17         }
18         return p;
19     } 
20     public TreeLinkNode GetNext(TreeLinkNode pNode)
21     {
22         TreeLinkNode p = pNode;
23         TreeLinkNode last = null;
24         while (p != null) {
25             if (p.left != null && p.left == last) {
26                 return p;
27             }
28             if (p.right != last && p.right != null) {
29                 return first(p.right);
30             }
31             last = p;
32             p = p.next;
33         }
34         return p;
35         
36     }
37 }