/// <summary>
/// We can use 2 linked list to do the operation in BFS fashion.
///
/// </summary>
/// <param name="head"></param>
/// <returns></returns>
public static List <SinglyLinkedList <BinaryTreeNode <int> > > CreateLinkedListOfTreeNodesAtEachDepth(BinaryTreeNode <int> head)
{
// the list of the linkedlist of nodes at each level
List <SinglyLinkedList <BinaryTreeNode <int> > > retList = new List <SinglyLinkedList <BinaryTreeNode <int> > >();
SinglyLinkedList <BinaryTreeNode <int> > lastLinkedList = new SinglyLinkedList <BinaryTreeNode <int> >();
lastLinkedList.AppendToEnd(head);
while (lastLinkedList.Head != null)
{
SingleLinkedListNode <BinaryTreeNode <int> > lastLinkedListNode = lastLinkedList.Head;
SinglyLinkedList <BinaryTreeNode <int> > newLinkedList = new SinglyLinkedList <BinaryTreeNode <int> >();
while (lastLinkedListNode != null)
{
if (lastLinkedListNode.Data.Left != null)
{
// Add the left child to the linked list
newLinkedList.AppendToEnd(lastLinkedListNode.Data.Left);
}
if (lastLinkedListNode.Data.Right != null)
{
// Add the right child to the linked list
newLinkedList.AppendToEnd(lastLinkedListNode.Data.Right);
}
lastLinkedListNode = lastLinkedListNode.NextNode;
}
retList.Add(lastLinkedList);
lastLinkedList = newLinkedList;
}
return(retList);
}