Populating Next Right Pointers in Each Node

 1 /**
 2  * Definition for binary tree with next pointer.
 3  * public class TreeLinkNode {
 4  *     int val;
 5  *     TreeLinkNode left, right, next;
 6  *     TreeLinkNode(int x) { val = x; }
 7  * }
 8  */
 9 public class Solution {
10     public void connect(TreeLinkNode root) {
11         if(root!=null)
12         {
13           TreeLinkNode current=root;
14           TreeLinkNode first=root;
15           List<TreeLinkNode> list=new ArrayList<TreeLinkNode>();
16           while(current!=null)
17           {
18              if(current.left!=null)
19                  list.add(current.left);//全部加入到list中 然后一个个指向next
20              if(current.right!=null)
21                  list.add(current.right);
22              
23              if(current.next!=null)
24                  current=current.next;
25              else
26                  break;
27 
28           }
29           for(int i=0;i<list.size()-1;i++)
30           {
31                  list.get(i).next=list.get(i+1);
32           }
33           
34           if(first.left!=null)
35           connect(first.left);//采用递归
36         }
37     }
38     
39 }