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. ~~~ ~~~ public class Solution { public ListNode add(ListNode l1, ListNode l2, int carry){ if(l1==null && l2==null){ return carry == 0? null : new ListNode(carry); } if(l1==null && l2!=null){ l1 = new ListNode(0); } if(l2==null && l1!=null){ l2 = new ListNode(0); } int sum = l1.val + l2.val + carry; ListNode curr = new ListNode(sum % 10); curr.next = add(l1.next, l2.next, sum / 10); return curr; } public ListNode addTwoNumbers(ListNode l1, ListNode l2) { return add(l1,l2,0); } } ~~~