题解 | #删除有序链表中重复的元素-II#

/**
 * struct ListNode {
 *    int val;
 *    struct ListNode *next;
 * };
 */
//哈哈，水过了，终于做完十个题了（苦笑）
class Solution {
public:
    /**
     * 
     * @param head ListNode类 
     * @return ListNode类
     */
    ListNode* deleteDuplicates(ListNode* head) {
        // write code here 
        if(head==NULL||head->next==NULL)
            return head;
        ListNode *really,*pre,*qre;
         ListNode* first = new ListNode(0);
        first->next=head;
        really=first;
        pre=head;
        qre=head->next;
        while(qre)
        {
            if(pre->val!=qre->val)
            {
                really->next=pre;
                really=really->next;
                pre=qre;
                qre=qre->next;
            }
            else{
                while(pre->val==qre->val&&qre)
                {
                    qre=qre->next;
                }
                if(qre==NULL)
                {
                    really->next=NULL;
                    return first->next;
                }
                pre=qre;
                qre=qre->next;
            }
        }
        really->next=pre;
        really->next->next=NULL;
        return first->next;
    }
};