leetCode(2):Remove Linked List Elements

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

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) {
        if(head==NULL)
    		return head;
    	ListNode* p=head;
    	ListNode* q=head;
    	ListNode* newHead=p;

    	while(p)
    	{
    		if(p->val==val)
    		{
    			if(q==p)
    			{
    				q=p->next;
    				delete p;
    				p=q;
    				newHead=p;
    			}
    			else
    			{
    				q->next=p->next;
    				delete p;
    				p=q->next;
    			}
    			continue;
    		}
    		q=p;
    		p=p->next;
    	}
    	return newHead;
    }
};