public ListNode deleteNode(ListNode head, ListNode tobeDelete) {

     if (head == null || head.next == null || tobeDelete == null) return null;

     if (tobeDelete.next != null) {

         // 要删除的节点不是尾节点

         ListNode next = tobeDelete.next;

         tobeDelete.val = next.val;

         tobeDelete.next = next.next;

     } else {

         ListNode cur = head;

         while (cur.next != tobeDelete) cur = cur.next;

         cur.next = null;

     }

     return head;

 }