1 public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
 2         ListNode head = new ListNode(0);
 3         ListNode result = head;
 4         
 5         int carry = 0 , tempSum = 0;
 6         while(l1 != null || l2 != null){
 7             int v1 , v2;
 8             v1 = (l1 != null) ? l1.val : 0;
 9             v2 = (l2 != null) ? l2.val : 0;
10             tempSum = v1 + v2 + carry;
11             carry = tempSum / 10;
12             tempSum = tempSum % 10;
13             head.next = new ListNode(tempSum);
14             head = head.next;
15             
16             l1 = (l1 != null) ? l1.next : null;
17             l2 = (l2 != null) ? l2.next : null;
18         }
19        
20         if(carry > 0) head.next = new ListNode(carry);
21         
22         return result.next;
23     }