题解 | #删除有序链表中重复的元素-II#

/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 *	ListNode(int x) : val(x), next(nullptr) {}
 * };
 */
#include <queue>
class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param head ListNode类 
     * @return ListNode类
     */
    ListNode* deleteDuplicates(ListNode* head) {
        if(head==nullptr||head->next==nullptr)
            return head;
        ListNode* res=new ListNode(-1);
        res->next=head;
        ListNode* pre=res;
        while(pre->next&&pre->next->next)
        {
            if(pre->next->val==pre->next->next->val)
            {
                int target=pre->next->val;
                while(pre->next&&pre->next->val==target)
                    pre->next=pre->next->next;
            }
            else
                pre=pre->next;
        }
        return res->next;
    }
};