CODE 16. Populating Next Right Pointers in Each Node II

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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

public void connect(TreeLinkNode root) {
	// Start typing your Java solution below
	// DO NOT write main() function
	if (null == root) {
		return;
	}
	bfs(root);
}

private void bfs(TreeLinkNode root) {
	Queue<TreeLinkNode> queue = new LinkedList<TreeLinkNode>();
	queue.offer(root);
	int queueNumber = 1;
	int layerNumber = 0;
	TreeLinkNode tempNode = null;
	while (!queue.isEmpty()) {
		tempNode = queue.poll();
		queueNumber--;
		if (null != tempNode.left) {
			queue.offer(tempNode.left);
			layerNumber++;
		}
		if (null != tempNode.right) {
			queue.offer(tempNode.right);
			layerNumber++;
		}
		if (queueNumber != 0) {
			tempNode.next = queue.peek();
		} else {
			tempNode.next = null;
		}

		if (queueNumber == 0 && layerNumber != 0) {
			queueNumber = layerNumber;
			layerNumber = 0;
		}
	}
}