Traverse Linked List from middle to left-right order using recursion

// A C# program to demonstrate
// the printing of Linked List middle
// to left right order
using System;

public class GFG
{
 
// A linked list node
public class Node
{
    public int data;
    public Node next;
};
 
// Given a reference (pointer to pointer)
// to the head of a list and an int, appends
// a new node at the end
static Node append(Node head_ref, int new_data)
{
    // Allocate node
    Node new_node = new Node();
 
    // Used in step 5
    Node last = head_ref;
 
    // Put in the data
    new_node.data = new_data;
 
    // This new node is going to be
    // the last node, so make next of
    // it as null
    new_node.next = null;
 
    // If the Linked List is empty,
    // then make the new node as head
    if (head_ref == null)
    {
        head_ref = new_node;
        return head_ref;
    }
 
    // Else traverse till the last node
    while (last.next != null)
        last = last.next;
 
    // Change the next of last node
    last.next = new_node;
    return head_ref;
}
 
// This function prints contents of
// linked list starting from head
static void printList(Node node)
{
    while (node != null) 
    {
        Console.Write( " " + node.data);
 
        if (node.next != null)
            Console.Write("->");
        node = node.next;
    }
}
 
// Function to get the size of linked list
static int getSize(Node head)
{
    if (head == null)
        return 0;
    return 1 + getSize(head.next);
}
 
// Utility function to print the Linked List
// from middle to left right order
static Node printMiddleToLeftRightUtil(Node head,
                          int counter, int lSize)
{
    // Base Condition
    // When size of list is odd
    if (counter == 1 && lSize % 2 != 0)
    {
 
        // Print node value
        Console.Write( head.data);
 
        // Returns address of next node
        return head.next;
    }
 
    // Base Condition
    // When size of list is even
    else if (counter == 1)
    {
 
        // Print node value
        // and next node value
        Console.Write(head.data);
        Console.Write( " , " + head.next.data);
 
        // Returns address of next to next node
        return head.next.next;
    }
    else
    {
 
        // Recursive function call and
        // store return address
        Node ptr = printMiddleToLeftRightUtil(head.next, 
                                    counter - 1, lSize);
 
        // Print head data
        Console.Write(" , " + head.data);
 
        // Print ptr data
        Console.Write(" , " + ptr.data);
 
        // Returns address of next node
        return ptr.next;
    }
}
 
// Function to print Middle to
// Left-right order
static void printMiddleToLeftRight(Node head)
{
    // Function call to get the size
    // Of Linked List
    int listSize = getSize(head);
 
    int middle = 0;
 
    // Store middle when Linked
    // List size is odd
    if (listSize % 2 != 0) 
    {
        middle = (listSize + 1) / 2;
    }
 
    // Store middle when Linked
    // List size is even
    else
    {
        middle = listSize / 2;
    }
 
    // Utility function call print
    // Linked List from Middle
    // to left right order
    Console.Write("Output : ");
 
    printMiddleToLeftRightUtil(head, middle, listSize);
}
 
// Driver code
public static void Main(String []args)
{
    // Start with the empty list
    Node head = null;
 
    // Insert 6. So linked list
    // becomes 6.null
    head = append(head, 6);
 
    // Insert 6. So linked list
    // becomes 6.4.null
    head = append(head, 4);
    head = append(head, 8);
    head = append(head, 7);
    head = append(head, 9);
    head = append(head, 11);
    head = append(head, 2);
 
    // After inserting linked list
    // becomes 6.4.8.7.9.11.2.null
    Console.Write("Created Linked list is: ");
 
    // Function to display Linked List content
    printList(head);
    Console.WriteLine();
 
    // Function call print Linked List from
    // Middle to left right order
    printMiddleToLeftRight(head);
}
}

// This code is contributed by Rajput-Ji