tree.java

/**
 * https://oj.leetcode.com/problems/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;
        if (root.left != null)
            root.left.next = root.right;
        if (root.right != null)
            root.right.next = (root.next == null) ? null : root.next.left;
        connect(root.left);
        connect(root.right);
    }
}

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