Create linked list of binary tree

/**
 * CreateLinkedListOfBT.java
 * 
 * Description: Given a binary tree, design an algorithm which creates a
linked
 * list of all the nodes at each depth (e.g., if you have a tree with
depth D,
 * you'll have D linked lists).
 * 
 * @author John Qiao <qiaoshun8888@gmail.com> Date: Jan 24, 2014
 */