public ListNode AddTwoNumbers(ListNode l1, ListNode l2)
{
ListNode last;
int num = ((l1?.val ?? 0) + (l2?.val ?? 0));
bool hasCarry = num / 10 > 0;
ListNode list = new ListNode(num % 10);
last = list;
l1 = l1.next;
l2 = l2.next;
for (; l1 != null || l2 != null || hasCarry; l1 = l1?.next, l2 = l2?.next)
{
num = (l1?.val ?? 0) + (l2?.val ?? 0) + (hasCarry ? 1 : 0);
hasCarry = num / 10 > 0;
last.next = new ListNode(num % 10);
last = last.next;
}
return(list);
}
public ListNode ToAddTwoNumbers(ListNode l1, ListNode l2)
{
return(ToAdd(l1, l2, 0));
}