【思路】

1.    將尾指標指向頭指標

2.    並將head指標向後移動k = count – k % count - 1位，phead = head.next就是新連結串列的頭指標

3.    將head.next置空，並返回phead

    public ListNode rotateRight(ListNode head, int k) {
        if (head == null) return head;
        ListNode phead = head;
        int count = 1;
        while (phead.next != null) {
            count++;
            phead = phead.next;
        }
        k = count - k % count - 1;
        phead.next = head;
        while (k-- > 0)
            head = head.next;
        phead = head.next;
        head.next = null;
        return phead;
    }
 

230 / 230 test cases passed. Runtime: 1 ms  Your runtime beats 14.33% of javasubmissions.

歡迎優化！