剑指 Offer 22. 链表中倒数第k个节点

让快指针和慢指针保持相同的距离

 public ListNode getKthFromEnd(ListNode head, int k) {
        ListNode fast = head;
        while (fast != null && k > 0) {
            fast = fast.next;
            k--;
        }
        ListNode slow = head;
        while (fast != null) {
            fast = fast.next;
            slow = slow.next;
        }

        return slow;
    }