Problem Populating Next Right Pointers in Each Node II

Problem Description:

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

Solution:

public void connect(TreeLinkNode root) {
if (root == null) {
return;
}

TreeLinkNode cur = root.next;
TreeLinkNode p  = null;
while (cur != null) {
if (cur.left != null) {
p = cur.left;
break;
}
if (cur.right != null) {
p = cur.right;
break;
}
cur = cur.next;
}

if (root.right != null) {
root.right.next = p;
}
if (root.left != null) {
root.left.next = root.right != null ? root.right : p;
}

connect(root.right);
connect(root.left);
}