public static void DeleteNodeAtEnd()
{
if (head == null)
{
// no element case
throw new Exception("Linked list is empty.");
}
else if (head.next == null)
{
// one element case
head = null;
}
else
{
// general case
DoublyListNode node = head, prev = node;
while (node.next != null)
{
prev = node;
node = node.next;
}
node.prev = null;
prev.next = null;
}
PrintList(head);
}
public static DoublyListNode CreateNode(int data)
{
DoublyListNode node = new DoublyListNode();
node.data = data;
node.prev = null;
node.next = null;
return(node);
}
public static void InsertNodeAtBeginning(int data)
{
// list is empty
DoublyListNode node = CreateNode(data);
if (head != null)
{
node.next = head;
head.prev = node;
}
head = node;
PrintList(head);
}
public static void InsertNodeAtPosition(int data, int position)
{
// position is the new index of the node after insertion in the list
if (head == null)
{
if (position == 0)
{
head = CreateNode(data);
}
else
{
throw new Exception("Position does not exist in the linked list.");
}
}
else
{
int listSize = GetListSize();
if (position < 0 || position >= listSize)
{
throw new Exception("Position does not exist in the linked list");
}
DoublyListNode newNode = CreateNode(data);
if (position == 0)
{
newNode.next = head;
head.prev = newNode;
head = newNode;
}
else
{
DoublyListNode node = head, prev = head;
int index = 0;
while (position != index && node.next != null)
{
prev = node;
node = node.next;
index++;
}
newNode.prev = prev;
newNode.next = node;
node.prev = newNode;
prev.next = newNode;
}
}
PrintList(head);
}
public static int GetListSize()
{
int length = 0;
if (head == null)
{
return(length);
}
else
{
DoublyListNode node = head;
while (node.next != null)
{
node = node.next;
length++;
}
return(length + 1);
}
}
public static void InsertNodeAtEnd(int data)
{
DoublyListNode newNode = CreateNode(data);
if (head == null)
{
head = newNode;
}
else
{
DoublyListNode node = head;
while (node.next != null)
{
node = node.next;
}
node.next = newNode;
newNode.prev = node;
}
PrintList(head);
}
public static void PrintList(DoublyListNode head)
{
if (head != null)
{
DoublyListNode node = head;
Console.WriteLine(Constants.resultPromptText);
Console.Write("X <- | " + head.data + " |");
node = node.next;
while (node != null)
{
Console.Write("<-> | " + node.data + " |");
node = node.next;
}
Console.Write("-> X\n");
}
else
{
throw new Exception("Linked list is empty");
}
}
public static void DeleteNodeAtPosition(int position)
{
if (head == null)
{
// linked list is empty
throw new Exception("the linked list is empty.");
}
else if (position < 0 || position >= GetListSize())
{
// invalid position case
throw new Exception("Position is invalid.");
}
else if (head.next == null)
{
// one element case
head = null;
}
else if (position == 0)
{
// generic case - position 0
DoublyListNode node = head.next;
head.next = null;
node.prev = null;
head = node;
}
else
{
// general case
DoublyListNode node = head, prev = head;
int index = 0;
while (position != index && node.next != null)
{
prev = node;
node = node.next;
index++;
}
prev.next = null;
node.prev = null;
}
PrintList(head);
}
public static void DeleteNodeAtBeginning()
{
if (head == null)
{
throw new Exception("Linked list is empty.");
}
else
{
if (head.next == null)
{
head = null;
}
else
{
DoublyListNode node = head.next;
head.next = null;
node.prev = null;
head = node;
}
}
PrintList(head);
}