Print reverse of a Linked List without actually reversing

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 hed->next
  2. print head->data

Implementation:

C

// C program to print reverse of a linked list
#include<stdio.h>
#include<stdlib.h>
   
/* Link list node */
struct Node
{
    int data;
    struct Node* next;
};
   
/* Function to reverse the linked list */
void printReverse(struct Node* head)
{
    // Base case  
    if (head == NULL)
       return;
  
    // print the list after head node
    printReverse(head->next);
  
    // After everything else is printed, print head
    printf("%d  ", head->data);
}
   
/*UTILITY FUNCTIONS*/
/* Push a node to linked list. Note that this function
  changes the head */
void push(struct Node** head_ref, char new_data)
{
    /* allocate node */
    struct Node* new_node =
            (struct Node*) malloc(sizeof(struct Node));
   
    /* put in the data  */
    new_node->data  = new_data;
   
    /* link the old list off the new node */
    new_node->next = (*head_ref);   
   
    /* move the head to pochar to the new node */
    (*head_ref)    = new_node;
   
/* Drier program to test above function*/
int main()
{
    // Let us create linked list 1->2->3->4
    struct Node* head = NULL;    
    push(&head, 4);
    push(&head, 3);
    push(&head, 2);
    push(&head, 1);
    
    printReverse(head);
    return 0;
}

Java

// Java program to print reverse of a linked list
class LinkedList
{
    Node head;  // head of list
  
    /* 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
        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;
    }
  
    /*Drier function to test the above methods*/
    public static void main(String args[])
    {
        // Let us 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)

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Improved By : Aashish Kumar 7


 
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