leetcode 203. 移除链表元素

 1 class Solution {
 2     public ListNode removeElements(ListNode head, int val) {
 3         if(head==null){
 4             return head;
 5         }
 6         ListNode iterator = head;
 7         ListNode pre = null;
 8         ListNode next = null;
 9         while(iterator!=null){
10             next = iterator.next;
11             if(iterator.val==val){
12                 if(pre==null){
13                     head=iterator.next;
14                 }else{
15                     pre.next=iterator.next;
16                 }
17             }else{
18                 pre=iterator;
19             }
20             iterator=next;
21         }
22         return head;
23     }
24 }