int val;

ListNode next;

ListNode(int x) {

val = x;

}

public ListNode addTwoNumbers(ListNode l1, ListNode l2) {

ListNode result = new ListNode(0);

ListNode cur = result;

while (l1 != null || l2 != null) {

cur.val += addTwoNodes(l1, l2);

if (cur.val >= 10) {

cur.val -= 10;

cur.next = new ListNode(1);

} else {

if (l1 != null && l1.next != null || l2 != null && l2.next != null)

cur.next = new ListNode(0);

}

cur = cur.next;

if (l1 != null)

l1 = l1.next;

if (l2 != null)

l2 = l2.next;

}

return result;

}

private int addTwoNodes(ListNode n1, ListNode n2) {

if (n1 == null)

return n2.val;

if (n2 == null)

return n1.val;

return n1.val + n2.val;

}