You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a linked list.

You may assume the two numbers do not contain any leading zero, except the number 0 itself.

Example:

Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8
Explanation: 342 + 465 = 807.
 1 public class Solution {
 2     public ListNode AddTwoNumbers(ListNode l1, ListNode l2) {
 3         int n = 0;
 4         int sum = l1.val + l2.val;
 5         n = sum > 9 ? 1 : 0;
 6         ListNode l3 = new ListNode(sum > 9 ? sum - 10 : sum);
 7         ListNode tmpNext1 = l1.next;
 8         ListNode tmpNext2 = l2.next;
 9         ListNode tmpNext3 = l3;
10         while (tmpNext1 != null || tmpNext2 != null) {
11             sum = n;
12             if (tmpNext1 != null) {
13                 sum += tmpNext1.val;
14                 tmpNext1 = tmpNext1.next;
15             }
16             if (tmpNext2 != null) {
17                 sum += tmpNext2.val;
18                 tmpNext2 = tmpNext2.next;
19             }
20             n = sum > 9 ? 1 : 0;
21             tmpNext3.next = new ListNode(sum > 9 ? sum - 10 : sum);
22             tmpNext3 = tmpNext3.next;
23         }
24         if (n > 0) {
25             tmpNext3.next = new ListNode(1);
26         }
27         return l3;
28     }
29 }