LeetCode 题解之Remove Duplicates from Sorted List II

1、题目描述

2、题目分析

链表的题，主要注意指针即可。

3、代码

  ListNode* deleteDuplicates(ListNode* head) {
         if (head == NULL || head->next == NULL)
             return head;

         ListNode *dummy = new ListNode();
         dummy->next = head;
         ListNode *p = head;
         ListNode *pre = dummy;

         while (p != NULL) {
             ListNode *tmp = p->next;
             if (tmp == NULL)
                 break;
             while (tmp->val == p->val) {
                 tmp = tmp->next;
                 if (tmp == NULL) {
                     pre->next = NULL;
                     break;
                 }
             }

             if (p->next == tmp) {
                 pre = p;
             }else {
                 pre->next = tmp;
             }
             p = tmp;

         }
         return dummy->next;

     }