Rotate List

Given a list, rotate the list to the right by k places, where k is non-negative.

For example: Given 1->2->3->4->5->NULL and k = 2, return 4->5->1->2->3->NULL.

Solution:

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
public class Solution {
    public ListNode rotateRight(ListNode head, int k) {
        if(head==null) return null;
        
        ListNode dummy = new ListNode(0);
        dummy.next = head;
        ListNode fast = dummy;
        ListNode slow = dummy;
        
        int size=0;
        while(fast.next!=null) {fast = fast.next; size++;}
        
        fast = dummy;
        for(int i=0; i<k%size; i++) fast = fast.next;
        
        while(fast.next!=null) {
            fast = fast.next;
            slow = slow.next;
        }
        
        fast.next = head;
        dummy.next = slow.next;
        slow.next = null;
        return dummy.next;
    }
}