public ListNode deleteNode(ListNode head, int val) {
    // 哨兵节点，用于处理删除头节点的情况
    ListNode sentry = new ListNode(0, head);
    // 遍历链表
    for (ListNode current = sentry; current.next != null; current = current.next) {
        if (current.next.val == val) {
            // 删除节点
            current.next = current.next.next;
            break; // 删除后直接退出循环
        }
    }
    return sentry.next; // 返回新链表的头节点
}

public ListNode removeNode(ListNode p,int val) {
    if (p == null) return null;
    if (p.val == val){
        return removeNode(p.next,val);
    }else{
        p.next = removeNode(p.next,val);
        return p;
    }
}