[Leetcode] Populating Next Right Pointers in Each Node

因为有了next指针，所以访问过的每一层都是可以遍历的，同样的方式可以得到下一层的情况

 

/**
 * Definition for binary tree with next pointer.
 * public class TreeLinkNode {
 *     int val;
 *     TreeLinkNode left, right, next;
 *     TreeLinkNode(int x) { val = x; }
 * }
 */
public class Solution {
    public void connect(TreeLinkNode root) {
        TreeLinkNode head=root;
        while(head!=null){
            TreeLinkNode tmphead=head;
            head=null;
            TreeLinkNode pre=null;
            while(tmphead!=null){
                if(tmphead.left!=null){
                    if(head==null){
                        pre=head=tmphead.left;
                    }
                    else{
                        pre.next=tmphead.left;
                        pre=tmphead.left;
                    }
                }
                if(tmphead.right!=null){
                    if(head==null){
                        pre=head=tmphead.right;
                    }else{
                        pre.next=tmphead.right;
                        pre=tmphead.right;
                    }
                }
                tmphead=tmphead.next;
            }
        }
    }
}

 

[1] http://www.cnblogs.com/felixfang/p/3647898.html