leetcode 002 Add Two Numbers

public class Solution {
    public static ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        ListNode l3 = new ListNode(-1);
        ListNode l3head=l3;
        if(l1==null)
            return l2;
        if(l2==null)
            return l1;
        int carry=0;
        
        while(l1!=null||l2!=null){
            if(l1!=null){
                carry +=l1.val;
                l1=l1.next;
            }
            if(l2!=null){
                carry += l2.val;
                l2=l2.next;
            }
            
            l3.next=new ListNode(carry%10);
            carry=carry/10;
            l3=l3.next;
            
        }
        
        if(carry==1){
            l3.next=new ListNode(1);
        }
        return l3head.next;
    }
    
    public static void main(String[] args) {
        ListNode l1=new ListNode(2);
        l1.next=new ListNode(4);
        l1.next.next=new ListNode(3);
        ListNode l2=new ListNode(5);
        l2.next=new ListNode(6);
        l2.next.next=new ListNode(4);
        ListNode anwer=addTwoNumbers(l1,l2);
        System.out.println(anwer.val+" "+anwer.next.val+" "+anwer.next.next.val);
        
    }
}