public void deleteNode(ListNode node) {
   if (node == null) {
     return;
   }
   node.val = node.next.val;
   node.next = node.next.next;
 }
 public static void main(String args[]) {
   ListNode head = null, p = null;
   for (int i = 1; i <= 10; i++) {
     if (i == 1) {
       head = p = new ListNode(1);
     } else {
       p.next = new ListNode(i);
       p = p.next;
     }
   }
   p = head;
   for (int i = 0; i < 5; i++) {
     p = p.next;
   }
   Q237 s = new Q237();
   s.printlnList(head);
   s.deleteNode(p);
   s.printlnList(head);
 }