[leetcode]117 populating Next right pointers in each Node II

https://oj.leetcode.com/problems/populating-next-right-pointers-in-each-node-ii/

http://blog.csdn.net/linhuanmars/article/details/23510601

/** * 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)  {                 // same as  https://oj.leetcode.com/problems/populating-next-right-pointers-in-each-node/         // But queue is not allowed                 TreeLinkNode curhead = root;         treelinknode nexthead = null;         treelinknode pre = null; // pre in next level                 // iterate cur level,  assign next level        while  (curhead !=  null)         {             // Start to iterate current level             TreeLinkNode cur = curhead;             while  (cur != null)              {                 if  (cur.left != null)                  {                     if  (nexthead == null)                           nexthead = cur.left;                     if  (pre != null)                           pre.next = cur.left;                     pre = cur.left;                 }                                  if  (cur.right != null)                  {                     // same logic as leftnode handling.                      if  (nexthead == null)                          nexthead =  cur.right;                     if  (Pre != null)                          pre.next = cur.right;                     pre  = cur.right;                 }                 cur = cur.next;            }                          // After iteration this level.             // Move to next nevel.             if  (nexthead != null)              {                 curhead = nexthead;                 nexthead = null;                 pre = null;             }            else             {                 // No next head.                 // We are finished.                 curhead = null;             }        }     }}

[leetcode]117 populating Next right pointers in each Node II