Print Doubly Linked list in Reverse Order

Last Updated : 26 Nov, 2019

Given a doubly-linked list of positive integers. The task is to print the given doubly linked list data in reverse order.

Examples:

Input: List = 1 <=> 2 <=>  3 <=>  4 <=>  5
Output: 5  4  3  2  1

Input: 10 <=> 20 <=> 30 <=> 40
Output: 40  30  20  10

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach:

Take a pointer to point to head of the doubly linked list.
Now, start traversing through the linked list till the end.
After reaching last node, start traversing in backward direction and simultaneously print the node->data.

Below is the implementation of the above approach:

C++

// C++ Program to print doubly 
// linked list in reverse order 
#include <bits/stdc++.h>
using namespace std;
  
// Doubly linked list node
struct Node {
    int data;
    struct Node* next;
    struct Node* prev;
};
  
// Function to print nodes of Doubly 
// Linked List in reverse order 
void reversePrint(struct Node** head_ref)
{
    struct Node* tail = *head_ref;
  
    // Traversing till tail of the linked list
    while (tail->next != NULL) {
        tail = tail->next;
    }
  
    // Traversing linked list from tail
    // and printing the node->data
    while (tail != *head_ref) {
        cout << tail->data << " ";
        tail = tail->prev;
    }
    cout << tail->data << endl;
}
  
/* UTILITY FUNCTIONS */
// Function to insert a node at the 
// beginging of the Doubly Linked List 
void push(struct Node** head_ref, int new_data)
{
    // allocate node 
    struct Node* new_node = (struct Node*)malloc(sizeof(struct Node));
  
    // put in the data 
    new_node->data = new_data;
  
    // since we are adding at the beginning, 
    // prev is always NULL 
    new_node->prev = NULL;
  
    // link the old list off the new node 
    new_node->next = (*head_ref);
  
    // change prev of head node to new node 
    if ((*head_ref) != NULL)
        (*head_ref)->prev = new_node;
  
    // move the head to point to the new node 
    (*head_ref) = new_node;
}
  
// Driver Code
int main()
{
    // Start with the empty list 
    struct Node* head = NULL;
  
    // Let us create a sorted linked list
    // to test the functions 
    // Created linked list will be 10->8->4->2 
    push(&head, 2);
    push(&head, 4);
    push(&head, 8);
    push(&head, 10);
  
    cout << "Linked List elements in reverse order : " << endl;
  
    reversePrint(&head);
  
    return 0;
}

Java

// Java Program to print doubly 
// linked list in reverse order 
class Sol
{
  
// Doubly linked list node 
static class Node
{ 
    int data; 
    Node next; 
    Node prev; 
}; 
  
// Function to print nodes of Doubly 
// Linked List in reverse order 
static void reversePrint( Node head_ref) 
{ 
    Node tail = head_ref; 
  
    // Traversing till tail of the linked list 
    while (tail.next != null)
    { 
        tail = tail.next; 
    } 
  
    // Traversing linked list from tail 
    // and printing the node.data 
    while (tail != head_ref)
    { 
        System.out.print( tail.data + " "); 
        tail = tail.prev; 
    } 
    System.out.println( tail.data ); 
} 
  
// UTILITY FUNCTIONS /
// Function to insert a node at the 
// beginging of the Doubly Linked List 
static Node push( Node head_ref, int new_data) 
{ 
    // allocate node 
    Node new_node = new Node(); 
  
    // put in the data 
    new_node.data = new_data; 
  
    // since we are adding at the beginning, 
    // prev is always null 
    new_node.prev = null; 
  
    // link the old list off the new node 
    new_node.next = (head_ref); 
  
    // change prev of head node to new node 
    if ((head_ref) != null) 
        (head_ref).prev = new_node; 
  
    // move the head to point to the new node 
    (head_ref) = new_node; 
    return head_ref;
} 
  
// Driver Code 
public static void main(String args[])
{ 
    // Start with the empty list 
    Node head = null; 
  
    // Let us create a sorted linked list 
    // to test the functions 
    // Created linked list will be 10.8.4.2 
    head = push(head, 2); 
    head = push(head, 4); 
    head = push(head, 8); 
    head = push(head, 10); 
  
    System.out.print( "Linked List elements in reverse order : " ); 
  
    reversePrint(head); 
} 
}
  
// This code is contributed by Arnab Kundu 

Python3

# Python3 Program to print doubly 
# linked list in reverse order 
import math
  
# Doubly linked list node
class Node: 
    def __init__(self, data): 
        self.data = data 
        self.next = None
  
# Function to print nodes of Doubly 
# Linked List in reverse order 
def reversePrint(head_ref):
    tail = head_ref
  
    # Traversing till tail of the linked list
    while (tail.next != None):
        tail = tail.next
  
    # Traversing linked list from tail
    # and pring the node.data
    while (tail != head_ref):
        print(tail.data, end = " ")
        tail = tail.prev
      
    print(tail.data)
  
# UTILITY FUNCTIONS 
# Function to insert a node at the 
# beginging of the Doubly Linked List 
def push(head_ref, new_data):
      
    # allocate node 
    new_node = Node(new_data)
  
    # put in the data 
    new_node.data = new_data
  
    # since we are adding at the beginning, 
    # prev is always None 
    new_node.prev = None
  
    # link the old list off the new node 
    new_node.next = head_ref
  
    # change prev of head node to new node 
    if (head_ref != None):
        head_ref.prev = new_node
  
    # move the head to po to the new node 
    head_ref = new_node
    return head_ref
  
# Driver Code
if __name__=='__main__':
      
    # Start with the empty list 
    head = None
  
    # Let us create a sorted linked list
    # to test the functions 
    # Created linked list will be 10.8.4.2 
    head = push(head, 2) 
    head = push(head, 4) 
    head = push(head, 8) 
    head = push(head, 10)
  
    print("Linked List elements in reverse order : ")
  
    reversePrint(head)
  
# This code is contributed by Srathore

C#

// C# Program to print doubly 
// linked list in reverse order
using System;     
      
class Sol
{
  
// Doubly linked list node 
public class Node
{ 
    public int data; 
    public Node next; 
    public Node prev; 
}; 
  
// Function to print nodes of Doubly 
// Linked List in reverse order 
static void reversePrint( Node head_ref) 
{ 
    Node tail = head_ref; 
  
    // Traversing till tail of the linked list 
    while (tail.next != null)
    { 
        tail = tail.next; 
    } 
  
    // Traversing linked list from tail 
    // and printing the node.data 
    while (tail != head_ref)
    { 
        Console.Write( tail.data + " "); 
        tail = tail.prev; 
    } 
    Console.WriteLine( tail.data ); 
} 
  
// UTILITY FUNCTIONS /
// Function to insert a node at the 
// beginging of the Doubly Linked List 
static Node push( Node head_ref, int new_data) 
{ 
    // allocate node 
    Node new_node = new Node(); 
  
    // put in the data 
    new_node.data = new_data; 
  
    // since we are adding at the beginning, 
    // prev is always null 
    new_node.prev = null; 
  
    // link the old list off the new node 
    new_node.next = (head_ref); 
  
    // change prev of head node to new node 
    if ((head_ref) != null) 
        (head_ref).prev = new_node; 
  
    // move the head to point to the new node 
    (head_ref) = new_node; 
    return head_ref;
} 
  
// Driver Code 
public static void Main(String []args)
{ 
    // Start with the empty list 
    Node head = null; 
  
    // Let us create a sorted linked list 
    // to test the functions 
    // Created linked list will be 10.8.4.2 
    head = push(head, 2); 
    head = push(head, 4); 
    head = push(head, 8); 
    head = push(head, 10); 
  
    Console.Write( "Linked List elements in reverse order : " ); 
  
    reversePrint(head); 
} 
}
  
// This code contributed by Rajput-Ji

Output:

Linked List elements in reverse order : 
2 4 8 10

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