Programa Java para rotar la lista doblemente enlazada por N Nodes

Java

// Java program to rotate a Doubly linked
// list counter clock wise by N times
class GfG {
 
/* Link list node */
static class Node
{
    char data;
    Node prev;
    Node next;
}
static Node head = null;
 
// This function rotates a doubly linked
// list counter-clockwise and updates the
// head. The function assumes that N is
// smallerthan size of linked list. It
// doesn't modify the list if N is greater
// than or equal to size
static void rotate( int N)
{
    if (N == 0)
        return;
 
    // Let us understand the below code
    // for example N = 2 and
    // list = a <-> b <-> c <-> d <-> e.
    Node current = head;
 
    // current will either point to Nth
    // or NULL after this loop. Current
    // will point to node 'b' in the
    // above example
    int count = 1;
    while (count < N && current != null)
    {
        current = current.next;
        count++;
    }
 
    // If current is NULL, N is greater
    // than or equal to count of nodes
    // in linked list. Don't change the
    // list in this case
    if (current == null)
        return;
 
    // current points to Nth node. Store
    // it in a variable. NthNode points to
    // node 'b' in the above example
    Node NthNode = current;
 
    // current will point to last node
    // after this loop current will point
    // to node 'e' in the above example
    while (current.next != null)
        current = current.next;
 
    // Change next of last node to previous
    // head. Next of 'e' is now changed to
    // node 'a'
    current.next = head;
 
    // Change prev of Head node to current
    // Prev of 'a' is now changed to node 'e'
    (head).prev = current;
 
    // Change head to (N+1)th node
    // head is now changed to node 'c'
    head = NthNode.next;
 
    // Change prev of New Head node to NULL
    // Because Prev of Head Node in Doubly
    // linked list is NULL
    (head).prev = null;
 
    // change next of Nth node to NULL
    // next of 'b' is now NULL
    NthNode.next = null;
}
 
// Function to insert a node at the
// beginning of the Doubly Linked List
static void push(char new_data)
{
    Node new_node = new Node();
    new_node.data = new_data;
    new_node.prev = null;
    new_node.next = (head);
    if ((head) != null)
        (head).prev = new_node;
head = new_node;
}
 
/* Function to print linked list */
static void printList(Node node)
{
    while (node != null && node.next != null)
    {
        System.out.print(node.data + " ");
        node = node.next;
    }
    if(node != null)
    System.out.print(node.data);
}
 
// Driver's Code
public static void main(String[] args)
{
    /* Start with the empty list */
    // Node head = null;
 
    /* Let us create the doubly
    linked list a<->b<->c<->d<->e */
    push( 'e');
    push( 'd');
    push('c');
    push('b');
    push( 'a');
 
    int N = 2;
 
    System.out.println("Given linked list ");
    printList(head);
    rotate( N);
    System.out.println();
    System.out.println("Rotated Linked list ");
    printList(head);
}
}
 
// This code is contributed by Prerna Saini