This video is part of the Linked List section in the GFG SDE Sheet.

In this video, we are given a linked list of size N. Our task is to reverse every k nodes (where k is an input to the function) in the linked list. If the number of nodes is not a multiple of k then left-out nodes, in the end, should be considered as a group and must be reversed.

Example :

Input:
LinkedList: 1->2->2->4->5->6->7->8
K = 4
Output: 4 2 2 1 8 7 6 5
 
Explanation: 
The first 4 elements 1,2,2,4 are reversed first and then the next 4 elements 5,6,7,8. Hence, the resultant linked list is 4->2->2->1->8->7->6->5.

Do check out:-

Article: https://www.geeksforgeeks.org/reverse-a-linked-list-in-groups-of-given-size/
Problem: https://practice.geeksforgeeks.org/problems/reverse-a-linked-list-in-groups-of-given-size/1
SDE Sheet: https://www.geeksforgeeks.org/sde-sheet-a-complete-guide-for-sde-preparation/