Big O week 4 day 1 p1

Problem: https://www.codingninjas.com/studio/problems/920454?topList=striver-sde-sheet-problems&leftPanelTab=1
Author: Sarthak Joleya

public class Solution {
    public static Node rotate(Node head, int k) {
        int n = 0;
        Node tmp = head;
        while(tmp != null){
            tmp = tmp.next;
            n++;
        }
        k %= n;
        if(k == 0) return head;
        tmp = head;
        Node ans=head;
        int x = n - k;
        while(x-- > 0){
            if(x == 0){
                ans = ans.next;
                tmp.next = null;
                break;
            }
            ans = ans.next;
            tmp = tmp.next;
        }
        tmp = ans;
        while(tmp.next != null){
            tmp = tmp.next;
        }
        tmp.next = head;
        return ans;
    }
}