1007. remove for single link list with head node

带虚拟头结点的单链表结点结构如下：
struct ListNode
{
int data;
ListNode *next;
};
链表类接口如下：
class List
{
public:
List()
{
head = new ListNode;
head->next = NULL;
}

~List(){    ListNode* curNode;    while( head->next )    {        curNode = head->next;        head->next = curNode->next;        delete curNode;    }           delete head;}//在链表第pos(pos>0)个结点之前插入新结点,新结点值为toadd //链表实际结点从1开始计数。//调用时需保证pos小等于链表实际结点数 void insert(int toadd, int pos)   //删除链表的第pos(pos>0)个结点    //链表实际结点从1开始计数。   //调用时需保证pos小等于链表实际结点数    void remove(int pos);// Data fieldListNode *head; //head指向虚拟头结点，head-next指向第一个实际结点

};

请实现如下函数：
void List::remove(int pos)

只提交remove函数实现，不要提交类定义及main函数。
Problem Source: 平时测验1

我的代码

// Problem#: 19147// Submission#: 4809302// The source code is licensed under Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License// URI: http://creativecommons.org/licenses/by-nc-sa/3.0/// All Copyright reserved by Informatic Lab of Sun Yat-sen Universityvoid List::insert(int toadd, int pos) {    ListNode *pre = head;    if (pos <= 0) return;    while (--pos && pre->next != NULL) {        pre = pre->next;    }    ListNode * add = new ListNode;    add->data = toadd;    if (pre->next != NULL) {        add->next = pre->next;    } else {        add->next = NULL;    }    pre->next = add;}