Java Program For Printing Reverse Of A Linked List Without Actually Reversing

Last Updated : 08 Jul, 2022
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Given a linked list, print reverse of it using a recursive function. For example, if the given linked list is 1->2->3->4, then output should be 4->3->2->1.
Note that the question is only about printing the reverse. To reverse the list itself see this 
Difficulty Level: Rookie 
 

reverse-a-link-list

Algorithm:

printReverse(head)
  1. call print reverse for head->next
  2. print head->data

Implementation: 

Java
// Java program to print reverse 
// of a linked list
class LinkedList
{
    // Head of list
    Node head;  

    // Linked list Node
    class Node
    {
        int data;
        Node next;
        Node(int d) 
        {
            data = d; 
            next = null; 
        }
    }

    // Function to print reverse of 
    // linked list 
    void printReverse(Node head)
    {
        if (head == null) return;

        // Print list of head node
        printReverse(head.next);

        // After everything else is printed,
        //  Print head
        System.out.print(head.data + " ");
    }

    // Utility Functions 

    // Inserts a new Node at front 
    // of the list. 
    public void push(int new_data)
    {
        /* 1 & 2: Allocate the Node &
                  Put in the data*/
        Node new_node = new Node(new_data);

        // 3. Make next of new Node as head 
        new_node.next = head;

        // 4. Move the head to point 
        // to new Node 
        head = new_node;
    }

    // Driver code
    public static void main(String args[])
    {
        // Create linked list 1->2->3->4
        LinkedList llist = new LinkedList();
        llist.push(4);
        llist.push(3);
        llist.push(2);
        llist.push(1);

        llist.printReverse(llist.head);
    }
}
// This code is contributed by Rajat Mishra 

Output: 

4 3 2 1

Time Complexity: O(n)

Space Complexity: O(n) for call stack since using recursion

Please refer complete article on Print reverse of a Linked List without actually reversing for more details!


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