Follow up for problem "Populating Next Right Pointers in Each Node".

What if the given tree could be any binary tree? Would your previous solution still work?

Note:

• You may only use constant extra space.

For example,
Given the following binary tree,

         1
       /  \
      2    3
     / \    \
    4   5    7

After calling your function, the tree should look like:

         1 -
>
 NULL
       /  \
      2 -
>
 3 -
>
 NULL
     / \    \
    4-
>
 5 -
>
 7 -
>
 NULL

tag: binary tree

/**
 * 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 = null;
        TreeLinkNode prev = null;
        TreeLinkNode cur = root;

        while (cur != null){

            // from current level, connect next level
            while (cur != null){
                if (cur.left != null){
                    if (prev != null){
                        prev.next = cur.left;
                    }
                    else{
                        head = cur.left;
                    }
                    prev = cur.left;
                }
                if (cur.right != null){
                    if (prev != null){
                        prev.next = cur.right;
                    }
                    else{
                        head = cur.right;
                    }
                    prev = cur.right;
                }
                cur = cur.next;
            }

            // move to next level
            cur = head;
            head = null;
            prev = null;
        }


    }
}