import java.util.Stack;

/**
 * created by zl on 2019/5/15 20:27
 */
public class medium_445_AddTwoNumbersII {
    public ListNode addTwoNumbers(ListNode l1, ListNode l2)
    {
        Stack<Integer> s1 = new Stack<Integer>();
        Stack<Integer> s2 = new Stack<Integer>();

        while(l1 != null)
        {
            s1.push(l1.val);
            l1 = l1.next;
        }
        while(l2 != null)
        {
            s2.push(l2.val);
            l2 = l2.next;
        }

        int sum = 0;
        ListNode list = new ListNode(0);
        while (!s1.empty() || !s2.empty())
        {
            if (!s1.empty())
                sum += s1.pop();
            if (!s2.empty())
                sum += s2.pop();
            list.val = sum % 10;
            ListNode head = new ListNode(sum/10);
            head.next = list;
            list = head;
            sum /= 10;
        }

        return list.val == 0 ? list.next : list;
    }
}