【leetcode】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

 

class Solution {
public:
    ListNode* removeElements(ListNode* head, int val) {
        if(head==NULL) return NULL;

          
     
        ListNode * p=head;
        ListNode * q=head->next;
      
        while(q)
        {
            if(q->val==val)
            {
                p->next=q->next;
                delete q;
                q=p->next;
            }else{
                p=p->next;
                q=q->next;
            }
        
        }

        if(head->val==val)
        {
            p=head;
            head=head->next;
            delete p;
        }
        return head;
    }
};