2. Add Two Numbers

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.

Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)

Output: 7 -> 0 -> 8/** * Definition for singly-linked list. * public class ListNode { *     int val; *     ListNode next; *     ListNode(int x) { val = x; } * } */public class Solution {    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {        int carry=0;        ListNode prev=new ListNode(0);        ListNode head=prev;        while(l1!=null||l2!=null||carry!=0)        {            ListNode cur = new ListNode(0);            int sum = ((l2 == null) ? 0 : l2.val) + ((l1 == null) ? 0 : l1.val) + carry;            cur.val = sum % 10;            carry = sum / 10;            prev.next = cur;            prev = cur;            l1 = (l1 == null) ? l1 : l1.next;            l2 = (l2 == null) ? l2 : l2.next;                   }        return head.next;    }}