2. Add Two Numbers

You are given two linked lists representing two non-negative numbers. 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.
Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8
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/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */
public class Solution {
    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        int carry = 0;
        ListNode p, head = new ListNode(0);
        p = head;
        while(l1!=null || l2!=null || carry!=0){
            int number = carry;
            if(l1 != null){
                number += l1.val;
                l1 = l1.next;
            }
            if(l2 != null){
                number += l2.val;
                l2 = l2.next;
            }
            if(number >9 ){
                carry = 1;
                number = number%10;
            }else{
                carry = 0;
            }
            p.next = new ListNode(number);
            p = p.next;
        }
        return head.next;
    }
}