題目203. 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

public class Solution {
    public ListNode removeElements(ListNode head, int val) {
        ListNode tempHead = new ListNode(1);
        tempHead.next = head;
        ListNode preNode = tempHead;
        ListNode node = preNode.next;
        while(node != null){
            if(node.val == val){
                preNode.next = node.next;
            }else{
                preNode = node;
            }
            node = preNode.next;
        }
        return tempHead.next;
    }
}