Reversing a linked list in batch of K

 Today I solved geeksforgeeks problem https://practice.geeksforgeeks.org/problems/reverse-a-linked-list-in-groups-of-given-size/1 to reverse a linked in list in batch of K. The code I wrote was very different from the one suggested by their editorial solution so I am sharing the code here for everyone's benefit.

class Solution
{
    public static Node reverse(Node node, int k)
    {
        Node head = null;
        Node oldtail = null;
        if(node==null) {
            return null;
        }
        int i=1;
        
        Node prev = node;
        node = node.next;
        Node newtail = prev;
        prev.next = null;
        while(node!=null) {
            if(i%k==0) {
                if(oldtail!=null) {
                    oldtail.next = prev;
                } else {
                    head = prev;
                }
                oldtail = newtail;
                prev = node;
                newtail = prev;
                node = node.next;
                prev.next=null;
                i++;
            } else {
                Node temp = node.next;
                node.next = prev;
                prev = node;
                node = temp;
                i++;
            }
        }
        if(oldtail!=null) {
            oldtail.next = prev;
        }
        if(head==null) {
            head=prev;
        }
        
        return head;
        
    }
}