leetcode 203

public class Solution {
    public static void main(String[] args) {
        ListNode head = new ListNode();
        head.val=7;
        head.next = null;
        for (int i = 0; i < 7; i++) {
            ListNode node = new ListNode(7,null);
            node.next = head.next;
            head.next = node;
        }
        ListNode p = removeElements(head,7);
        while(p!=null){
            System.out.print(p.val+" ");
            p = p.next;
        }
        System.out.println();
    }
    public static ListNode removeElements(ListNode head, int val) {
        ListNode fast;
        ListNode slow;
        if(head==null){
            return head;
        }
        ListNode headNode = new ListNode();
        headNode.next = head;
        ListNode p = headNode;
        while(p.next!=null){
            if(p.next.val==val){
                p.next = p.next.next;
            }
            else{
                p = p.next;
            }
        }
        return headNode.next;
    }
}