/// <summary>
/// This method uses last element as pivot element for partitioning.
/// </summary>
/// <param name="head"></param>
/// <param name="lastNode"></param>
/// <returns></returns>
private static DLLNode Partition(DLLNode head, DLLNode lastNode)
{
DLLNode current = head;
DLLNode pivotNode = lastNode;
DLLNode prev = null;
int temp;
while (current != pivotNode)
{
if (current.Data < pivotNode.Data)
{
prev = (prev == null) ? head : prev.Next;
temp = current.Data;
current.Data = prev.Data;
prev.Data = temp;
}
current = current.Next;
}
prev = (prev == null) ? head : prev.Next;
temp = prev.Data;
prev.Data = pivotNode.Data;
pivotNode.Data = temp;
return(prev.Next);
}
public void Display()
{
DLLNode temp = Head;
while (temp != null)
{
Console.WriteLine(temp.Data);
temp = temp.Next;
}
}
public DLLNode GetLastNode()
{
DLLNode temp = Head;
while (temp.Next != null)
{
temp = temp.Next;
}
return(temp);
}
public static void SortUtil(DLLNode head, DLLNode last)
{
if ((head == null) || (last == null) || (head.Next == last))
{
return;
}
DLLNode pivotNode = Partition(head, last);
SortUtil(head, pivotNode.Prev);
SortUtil(pivotNode.Next, last);
}
public void Push(int data)
{
if (Head == null)
{
Head = new DLLNode {
Data = data
};
}
else
{
DLLNode newNode = new DLLNode {
Data = data
};
newNode.Next = Head;
Head.Prev = newNode;
Head = newNode;
}
}
public static void Sort(DLList dllList)
{
DLLNode lastNode = dllList.GetLastNode();
SortUtil(dllList.Head, lastNode);
}
