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(0);
        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;
        
    }