leetcode82 Remove Duplicates from Sorted List II

Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.

For example,
Given 1->2->3->3->4->4->5, return 1->2->5.
Given 1->1->1->2->3, return 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)
            return NULL;
        ListNode *ans=new ListNode(0);
        ListNode *p=ans;
        int cur=head->val;
        int count=1;
        head=head->next;
        while(head)
        {
            if(head->val!=cur)
            {
                if(count==1)
                {
                    ListNode *temp=new ListNode(cur);
                    p->next=temp;
                    p=p->next;
                }
                cur=head->val;
                count=1;
            }
            else
            {
                count++;
            }
            head=head->next;
        }
                if(count==1)
                {
                    ListNode *temp=new ListNode(cur);
                    p->next=temp;
                    p=p->next;
                }
        return ans->next;
    }
};