1. Node * addTwoLists(Node * first, Node * second) {
2.   Node * res = NULL;
3.   Node * temp;
4.   Node * prev = NULL;
5.   int carry = 0, sum = 0;
6.   while (first != NULL || second != NULL) {
7.     sum = carry;
8.     sum += first != NULL ? first -> data : 0;
9.     sum += second != NULL ? second -> data : 0;
10.     if (sum >= 10) {
11.       carry = 1;
12.     } else {
13.       carry = 0;
14.     }
15.     sum %= 10;
16.     temp = newNode(sum);
17.     if (res != NULL) {
18.       prev -> next = temp;
19.     } else {
20.       res = temp;
21.     }
22.     prev = temp;
23.     if (first) {
24.       first = first -> next;
25.     }
26.     if (second) {
27.       second = second -> next;
28.     }
29.   }
30.  
31.   if (carry > 0)
32.     temp -> next = newNode(carry);
33.   return res;
34. }
35.  
36. Node * reverse(Node * head) {
37.   if (head == NULL || head -> next == NULL) {
38.     return head;
39.   }
40.   Node * rest = reverse(head -> next);
41.   head -> next -> next = head;
42.   head -> next = NULL;
43.   return rest;
44. }
45.  
46. Node * solve(Node * list1, Node * list2) {
47.   list1 = reverse(list1);
48.   list2 = reverse(list2);
49.   Node * added = addTwoLists(list1, list2);
50.   return added;
51. }