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 }