删除链表元素

class Solution {
    public ListNode removeElements(ListNode head, int val) {
        ListNode dummy = new ListNode(0, head);
        ListNode curr = head;
        ListNode pre = dummy;
        ListNode next;
        while(curr != null){
            next = curr.next;
            if(curr.val == val){
                pre.next = next;
            }else{
                pre = curr;
            }
            curr = next;
        }
        return dummy.next;
    }
}