Leetcode-Remove Duplicates from Sorted List II（二级指针）

Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.

For example,
Given 1->2->3->3->4->4->5, return 1->2->5.
Given 1->1->1->2->3, return 2->3.

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/** * 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 **runner = &head;                if(!head || !head->next)return head;                while(*runner)        {            if((*runner)->next && (*runner)->next->val == (*runner)->val)            {                ListNode *temp = *runner;                while(temp && (*runner)->val == temp->val)                    temp = temp->next;                                *runner = temp;            }            else                runner = &((*runner)->next);        }                return head;    }};