Remove Linked List Elements

问题：

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

思路：

　　简单的链表操作

我的代码：

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