452.Remove Linked List Elements

1.Description(Naive)

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

Example

Given1->2->3->3->4->5->3, val = 3, you should return the list as1->2->4->5

2.Code

public ListNode removeElements(ListNode head, int val) {
        if(head==null){
            return head;
        }
        ListNode dummy=new ListNode(0);
        dummy.next=head;
        ListNode prev=dummy;
        ListNode current=head;
        while(current!=null){
            if(current.val==val){
                prev.next=current.next;
                //注意这个时候因为中间删了一个值，所以prev还是不变的，只变了current
                current=current.next;
            }
            else{
                prev=prev.next;
                current=current.next;
            }
        }
        return dummy.next;
    }