LeetCode 116. Populating Next Right Pointers in Each Node

/**
* 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) {
if (root == null) return;
root.next = null;
nodeConnect(root.left, root.right);
}

public static void nodeConnect(TreeLinkNode left, TreeLinkNode right) {
if (left == null) return;
left.next = right;
right.next = null;
nodeConnect(left.left, left.right);
nodeConnect(left.right, right.left);
nodeConnect(right.left, right.right);
}
}