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.
Tips：删除链表中的一个结点，但是仅给出一个需要删除的链表。
解决思路：将要删除的结点node的后一个结点的val赋值给要node，再删除node.next。
public void deleteNode(ListNode node) { if(node==null ||node.next==null){ return ; } node.val=node.next.val; node.next=node.next.next; }