leetcode-Remove Linked List Elements

Difficulty: Easy

Remove all elements from a linked list of integers that have valueval.

Example
Given: 1 --> 2 --> 6 --> 3 --> 4 --> 5 --> 6, val = 6
Return: 1 --> 2 --> 3 --> 4 --> 5

/** * Definition for singly-linked list. * struct ListNode { *     int val; *     ListNode *next; *     ListNode(int x) : val(x), next(NULL) {} * }; */class Solution {public:    ListNode* removeElements(ListNode* head, int val) {        ListNode *dump=new ListNode(-1);        dump->next=head;        ListNode *p=dump;        ListNode *q=head;        while(q){            bool is_dele=false;            if(q->val==val){                is_dele=true;                while(q->next&&q->val==q->next->val)                    q=q->next;            }            if(is_dele)                p->next=q->next;            else                p=p->next;            q=q->next;        }        return dump->next;    }};