If the reversing requires to keep the link list nodes at their same position, technique 2 will fail. I am trying to reverse a linked list. The reversing of the linked list begins by initializing the ptrA to Null. Iterate through the linked list. Example 2: Input: LinkedList: 2->7->8->9->10 Output: 10 9 8 7 2 Explanation: After reversing the list, elements are 10->9->8->7->2. Every … Method 1 is the most straight forward and it can be implemented pretty quickly. brightness_4 Objective: Reverse the given linked list. Below is the implementation of this method. The loop traverses the whole linked list once. Keep 3 pointers on previous node, current node, next node. If the linked list has 0 or only 1 node, then it does not make sense to reverse the list, so we can simply return then and there. We have reversed the linked list by changing the links between them. Recursively Reversing a linked list (A simple implementation) Iteratively Reverse a linked list using only 2 pointers (An Interesting Method), References: http://cslibrary.stanford.edu/105/LinkedListProblems.pdf. Please use ide.geeksforgeeks.org, generate link and share the link here. Start popping the nodes(value and address) and store them in the same order until the stack is empty. Experience. Writing code in comment? To reverse the given linked list we will use three extra pointers that will be in the … We need to reverse the list by changing links between nodes. close, link without having to create a new list or to work on multiple iterations or to modify the existing data structure (not converting it into a double linked list) This method of reversing the linked list is performed in a single traverse through the link list. We use cookies to ensure you have the best browsing experience on our website. Given only a pointer to a node to be deleted in a singly linked list, how do you delete it? Easy. At the beginning, the pointer of the is . Given pointer to the head node of a linked list, the task is to reverse the linked list. In loop, do following. In this article, 3 different methods of reversing a linked list are demonstrated. Given a linked list of N nodes.The task is to reverse this list. 5627107Add to ListShare. After we reverse the linked list, the head will point to the last element of the original linked list, and the pointer of each element will point to the previous element of the original linked list: In Java, we have a LinkedList class to provide a doubly-linked list implementation of the List and Deque interfaces. Initialize previous and the next pointer as NULL. The head node of the linked list will be the last node of the linked list and the last one will be the head node. If the linked list has 0 or only 1 node, then it does not make sense to reverse the list, so we can simply return then and there. Technique 1 In this way, a new linked list will be created and all the items of the first linked list will be added to the new linked list in reverse … head should now point to its next node i.e. Also, we discussed two algorithms that can reverse a linked list in linear time. Input: A Linked List Output: Reversed Linked List Example: Input : ->30->25->20->15->10->5 Reversed : ->5->10->15->20->25->30. In the end, the pointer will point to the new head element of the reversed linked list. However, we'll use a general singly-linked list data structure in this tutorial. We need to reverse the list by changing the links between nodes. Since each element only has one reference to the next element, we need another pointer, ,  to store the next element before changing the pointer. NOTE : Click Reverse a Linked List – Part 2 to see the another implementation of this problem. Let us get over with the base cases first. after you are done, get the pointer of the first node after your original list to point at a reversed list. Assuming we have >=2 nodes now, we can do the following. The next of ptrB is linked to ptrA because the ptrB which is pointing to the first node becomes the tail node in the reversed list. This is the code I have come up with: public static void Reverse(ref Node root) { Node tmp = root; Node nroot = null; Node prev = null; while (tmp != null) { //Make a new node and copy tmp nroot = new Node(); nroot.data = tmp.data; nroot.next = prev; … Therefore, we can reverse the last two elements, and , with the above two operations. Given pointer to the head node of a linked list, the task is to reverse the linked list. Attention reader! Let us get over with the base cases first. Thanks to Gaurav Ahirwar for suggesting this solution. In this tutorial, we showed a sample linked list and its reversal. Can we reverse a linked list in less than O(n)? Follow up: A linked list can be reversed either iteratively or recursively. 206. Store the nodes(values and address) in the stack until all the values are entered. Assuming we have >=2 nodes now, we can do the following. Input: Head of following linked list 1->2->3->4->5->NULL Recursively Reversing a linked list (A simple implementation) Last Updated: 26-11-2019 Given pointer to the head node of a linked list, the task is to recursively reverse the linked list. Below is the implementation of the above approach: edit Therefore, the running time is , where is the total number of elements of the linked list. Then, the linked list becomes our simpler case. Input: Head of following linked list 1->2->3->4->NULL Output: Linked list should be changed to, 4->3->2->1->NULL, Input: Head of following linked list 1->2->3->4->5->NULL Output: Linked list should be changed to, 5->4->3->2->1->NULL. Each element of a linked list contains a data field to store the list data and a pointer field to point to the next element in the sequence. acknowledge that you have read and understood our, GATE CS Original Papers and Official Keys, ISRO CS Original Papers and Official Keys, ISRO CS Syllabus for Scientist/Engineer Exam, Write a function that counts the number of times a given int occurs in a Linked List, Add two numbers represented by linked lists | Set 1, Add two numbers represented by linked lists | Set 2, Add Two Numbers Represented by Linked Lists | Set 3, Reverse a Linked List in groups of given size | Set 1, Reverse a Linked List in groups of given size | Set 2, Reverse alternate K nodes in a Singly Linked List, Alternate Odd and Even Nodes in a Singly Linked List, Alternating split of a given Singly Linked List | Set 1, Program for n’th node from the end of a Linked List, Find the middle of a given linked list in C and Java, Stack Data Structure (Introduction and Program), Doubly Linked List | Set 1 (Introduction and Insertion), Recursively Reversing a linked list (A simple implementation), Iteratively Reverse a linked list using only 2 pointers (An Interesting Method), http://cslibrary.stanford.edu/105/LinkedListProblems.pdf, XOR Linked List - A Memory Efficient Doubly Linked List | Set 1, XOR Linked List – A Memory Efficient Doubly Linked List | Set 2, Merge a linked list into another linked list at alternate positions, Convert singly linked list into circular linked list, Difference between Singly linked list and Doubly linked list, Convert Singly Linked List to XOR Linked List, Create new linked list from two given linked list with greater element at each node, Check if a linked list is Circular Linked List, Generate Linked List consisting of maximum difference of squares of pairs of nodes from given Linked List, Given a linked list, reverse alternate nodes and append at the end, Merge two sorted linked lists such that merged list is in reverse order, Iteratively Reverse a linked list using only 2 pointers (An Interesting Method). Reverse a singly linked list. Example 1: Input: LinkedList: 1->2->3->4->5->6 Output: 6 5 4 3 2 1 Explanation: After reversing the list, elements are 6->5->4->3->2->1. Do it in-place. Reverse a Linked List using Iterative Solution. Example: Input:1->2->3->4->5->NULLOutput:5->4->3->2->1->NULL. However it uses lots of system resources. In Computer Science, a linked list is a linear data structure in which a pointer in each element determines the order. Run a loop till current points to NULL. Implement a stack using singly linked list, Delete a Linked List node at a given position, Implementing a Linked List in Java using Class, Circular Linked List | Set 1 (Introduction and Applications), Search an element in a Linked List (Iterative and Recursive), Find Length of a Linked List (Iterative and Recursive), Write Interview The function should take one input (head of the list) and return the new head of the list. We can extend this solution to a recursive algorithm of reversing a linked list staring with a element. Don’t stop learning now. Approach: Iterative: Create 3 nodes, currNode, PrevNode and nextNode. The recursive algorithm also traverses the whole linked list once. code, Time Complexity: O(n) Space Complexity: O(1). Create two more pointers other than head namely prevNode and curNode that will hold the reference of previous node and current node respectively. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.

reverse a linked list

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