leetcode83---Remove Duplicates from Sorted List(删除重复元素)

Given 1->1->2, return 1->2.
Given 1->1->2->3->3, return 1->2->3.

/**
* Definition for singly-linked list.
* struct ListNode {
*     int val;
*     ListNode *next;
*     ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
ListNode* deleteDuplicates(ListNode* head) {
if(head==NULL || head->next==NULL) return head;//
ListNode* prehead = new ListNode(0);
prehead->next = head;//前置头结点！！！
ListNode* pre = prehead;
ListNode* cur = head;
while(cur->next)//
{
if(cur->val == cur->next->val)
{
pre->next = cur->next;
}
else
{
pre = pre->next;
}
cur = cur->next;
}
return prehead->next;
}
};