Reverse a Linked List in Groups of k

Given the head of a linked list, reverse the nodes of the list k at a time and return the modified list. If the number of nodes is not a multiple of k, then left-out nodes will remain as is. Input Format: The first line contains an integer n, the number of nodes in the linked list. The second line contains k, the size of the groups. The next n lines contain integers, the values of the nodes. Output Format: Print the values of the modified linked list. Example: Input: 5 3 1 2 3 4 5 Output: 3 2 1 4 5