Rotate List

1public ListNode rotateRight(ListNode head, int k) {
2    if (head == null || head.next == null) return head;
3
4    // Calculate the length of the list
5    int length = 1;
6    ListNode tail = head;
7    while (tail.next != null) {
8        tail = tail.next;
9        length++;
10    }
11
12    // Make the list circular
13    tail.next = head;
14
15    // Find the new head and tail
16    k = k % length;
17    int stepsToNewHead = length - k;
18    ListNode newTail = head;
19    for (int i = 0; i < stepsToNewHead - 1; i++) {
20        newTail = newTail.next;
21    }
22    ListNode newHead = newTail.next;
23    newTail.next = null;
24
25    return newHead;
26}