problem:
Write a function to delete a node (except the tail) in a singly linked list, given only access to that node.

Given linked list – head = [4,5,1,9], which looks like following:

Example 1:

Input: head = [4,5,1,9], node = 5
Output: [4,1,9]
Explanation: You are given the second node with value 5, the linked list should become 4 -> 1 -> 9 after calling your function.

Example 2:

Input: head = [4,5,1,9], node = 1
Output: [4,5,9]
Explanation: You are given the third node with value 1, the linked list should become 4 -> 5 -> 9 after calling your function.
tip:
删除链表中指定的结点，但是没有给头结点和前结点，只给定了要删除额结点。
solution:

class Solution {
public:
    void deleteNode(ListNode* node) {
        node->val = node->next->val;
        ListNode* del = node->next;
        node->next=node->next->next;
        delete del;//这句其实有没有都可以
    }
};