leetcode 82. 删除排序链表中的重复元素 II

/**
 * 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) {
        ListNode* h=new ListNode(-1);
        ListNode* h1=h;
        h->next=head;
        if(h==NULL||h->next==NULL)return head;
        while(h->next!=NULL&&h->next->next!=NULL){

            if(h->next->next->val==h->next->val){
                
                h->next=h->next->next;
               
                if(h->next->next==NULL||h->next->next->val!=h->next->val){
                    h->next=h->next->next;
                }
                
            }else{
                h=h->next;
            }
        }
        return h1->next;
    }
};