k is a positive integer that is less than or equal to the length of l. If the number of nodes in the linked list is not a multiple of k, then the nodes that are left out at the end should remain as-is. (K is input value) We use cookies to ensure you have the best browsing experience on our website. The method 1 reverses the first k node and then moves the pointer to k nodes ahead. Problem. K Reverse In Linked List . If you forget about this, your linked list has a cycle in it. Examples: Input: Head of following linked list 1->2->3->4->NULL Output: Linked list should be changed to, 4->3->2->1->NULL. Also, each node’s … Solution : We have a pointer q which points to the head of the list initially. Let us take an example of the linked list as shown in the below diagram: Now let's follow the following steps to reverse the given linked list: Let the first node be the current node which holds the reference to the head node as shown in the diagram below. Given a linked list, write a function to reverse every k nodes (where k is an input to the function). Try First, Check Solution later 1. NOTE : The length of the list is divisible by K Example : Given linked list 1 -> 2 -> 3 -> 4 -> 5 -> 6 and K=2, You should return 2 -> 1 -> 4 -> 3 -> 6 -> 5 Try to solve the problem using constant extra space. code. Could you implement both? Given a linked list and a number k. Reverse every k nodes in the list. You may not alter the values in the list's nodes, only nodes … Solution : We have a pointer q which points to the head of the list initially. In Reverse Nodes in K-Group problem we have given a linked list, Reverse the linked list in a group of k and return the modified list. Now, when our linked list is partitioned into groups, we need to reverse each group. Assuming we have >=2 nodes now, we can do the following. Here, I want to reverse every k elements of the linked list recursively. Method 1 (Process 2k nodes and recursively call for rest of the list) Here, I want to reverse every k elements of the linked list recursively. Attention reader! Give the complexity of your algorithm. 1) Traverse the linked list till K-th point. Problem. A linked list, the task is to reverse the linked list. Inputs: 1->2->3->4->5->6->7->8->NULL and k = 5 Output: 5->4->3->2->1->8->7->6->NULL. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready. Given a linked list, reverse the nodes of a linked list k at a time and return its modified list. For example, Given pointer to the head node of a linked list and a number K, the task is to reverse the first K nodes of the linked list. Please write comments if you find the above code/algorithm incorrect, or find other ways to solve the same problem. By using our site, you Given a singly linked list, reverse every K nodes of the linked list and return the head of the modified linked list. Don’t stop learning now. k is a positive integer and is less than or equal to the length of the linked list. We use cookies to ensure you have the best browsing experience on our website. Now q points to (k+1)th node and we call the same procedure on it. Special care has to be taken while linking reversed groups with each other. Once the operation is performed, pointer to the head … Now as this process is completed our linked list is reversed into groups of given size. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready. Example : Input 1->2->3->4->5->6 and k = 2 Output 2->1->4->3->6->5. Output Reverse the linked list and return the head of the modified list. Approach: Earlier we have seen how to reverse a linked list, solution for reverse the linked list in groups of size will be extension of this solution. Attention reader! If the nodes are not multiple of k then reverse the remaining nodes. Example : Input 1->2->3->4->5->6 and k = 2 Output 2->1->4->3->6->5. Please write to us at contribute@geeksforgeeks.org to report any issue with the above content. For k = 2, you should return: 2->1->4->3->5. Reverse a Linked List in groups of given size ‘K’ Example. Writing code in comment? Experience, Reverse the first sub-list of size k. While reversing keep track of the next node and previous node. Given pointer to the head node of a linked list, the task is to reverse the linked list. Example: Input: 1->2->3->4->5->NULL, m = 2, n = 4 Output: 1->4->3->2->5->NULL For k = 3, you should return: 3->2->1->4->5. We use cookies to ensure you get the best experience on our website. This challenge is part of a tutorial track by MyCodeSchool and is accompanied by a video lesson. In this way, the head of the linked list will point to the last node of the linked list. Let the pointer to the next node be. Given a linked list, reverse the nodes of a linked list k at a time and return its modified list. 3. Given a linked list, reverse the nodes of a linked list k at a time and return its modified list.. k is a positive integer and is less than or equal to the length of the linked list. Interview prepration- Our coding bootcamp focusing on online coding challenges and competitive programming, delivered to. ; Reverse first ‘k’ nodes of the linked list, the k th node will be a new head, return it. Reverse a linked list. Example: Input: 1->2->3->4->5->NULL Output: 5->4->3->2->1->NULL Follow up: A linked list can be reversed either iteratively or recursively. Don’t stop learning now. By using our site, you Time Complexity: O(n) Input: Head of following linked list 1->2->3->4->5->NULL Examples: Inputs: 1->2->3->4->5->6->7->8->NULL and k = 3 Output: 3->2->1->6->5->4->8->7->NULL. 2. Find Complete Code at GeeksforGeeks Article: This video is contributed by komal kungwani Please Like, Comment and Share the Video among your friends. A common interview question asked at larger companies, reversing a linked list is a problem I’ve seen trip up a lot of engineers throughout my … Advance this k times in a while loop and keep reversing the list. Given a linked list, write a function to reverse every alternate k nodes (where k is an input to the function) in an efficient way. In this C++ program to reverse a linked list in groups of given size we first need to partition linked list in groups of given size. You may not alter the values in the nodes, only nodes itself may be changed. Approach 1: Iterative. If the number of nodes is not a multiple of k(less than k), then we do not need to reverse those remaining nodes. Given a linked list, reverse the nodes of a linked list k at a time and return its modified list. We need to reverse the list by changing the links between nodes. Let us get over with the base cases first. K Reverse In Linked List . check also Reversal of a linked list Given a linked list, write a function to reverse every k nodes (where k is an input to the function). ; Make a recursive call to rest of the list and attach it to the last node. The value of k is always smaller or equal to the length of the linked list and it is always greater than 0. Reverse a singly linked list. Given a singly linked list, reverse every K nodes of the linked list and return the head of the modified linked list. Example: Input: 1->2->3->4->5->NULL Output: 5->4->3->2->1->NULL Follow up: A linked list can be reversed either iteratively or recursively. Reverse alternate K nodes in a Singly Linked List. 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, 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, Write a function that counts the number of times a given int occurs in a Linked List, Stack Data Structure (Introduction and Program), Doubly Linked List | Set 1 (Introduction and Insertion), Reverse alternate K nodes in a Singly Linked List - Iterative Solution, Given a linked list, reverse alternate nodes and append at the end, 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, C Program to reverse each node value in Singly Linked List, Reverse a singly Linked List in groups of given size | Set 3, Merge a linked list into another linked list at alternate positions, Append odd position nodes in reverse at the end of even positioned nodes in a Linked List, Delete all Prime Nodes from a Singly Linked List, Sum and Product of the nodes of a Singly Linked List which are divisible by K, Sum and Product of all Prime Nodes of a Singly Linked List, Product of the nodes of a Singly Linked List, Delete all Prime Nodes from a Circular Singly Linked List, Find the common nodes in two singly linked list, Count of Prime Nodes of a Singly Linked List, Sum and Product of the nodes of a Circular Singly Linked List which are divisible by K, Delete all Non-Prime Nodes from a Singly Linked List, Delete nodes which have a greater value on right side, 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), Find Length of a Linked List (Iterative and Recursive), Write Interview
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