203. Remove Linked List Elements (List)

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) {
        ListNode* newHead = new ListNode(0);
        newHead->next = head;
        ListNode* pre = newHead;
        ListNode* cur = head;
        
        while(cur){
            if(cur->val == val){
                pre->next = cur->next;
            }
            else{
                pre = pre->next;
            }
            cur = cur->next;
        }
        return newHead->next; 
    }
};