Write a function to delete a node (except the tail) in a singly linked list, given only access to that node.
Supposed the linked list is 1 -> 2 -> 3 -> 4 and you are given the third node with value 3, the linked list should become 1 -> 2 -> 4 after calling your function.
思路，之前就看过这种怎么删除链表的一个节点，就是不利用外来引用也不需要遍历的情况下。但是这个算法就要求不能是尾节点。
public void deleteNode(ListNode node) { if (node == null || node.next == null) return; node.val = node.next.val; node.next = node.next.next; }