### LeetCode Challenge #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 contains a single digit. Add the two numbers and return the sum as a linked list.

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

Example 1:

```Input: l1 = [2,4,3], l2 = [5,6,4]
Output: [7,0,8]
Explanation: 342 + 465 = 807.
```

Example 2:

```Input: l1 = [0], l2 = [0]
Output: [0]
```

Example 3:

```Input: l1 = [9,9,9,9,9,9,9], l2 = [9,9,9,9]
Output: [8,9,9,9,0,0,0,1]
```

Constraints:

• The number of nodes in each linked list is in the range `[1, 100]`.
• `0 <= Node.val <= 9`
• It is guaranteed that the list represents a number that does not have leading zeros.
##### Video Solution
###### Java Solution
```				```
class Solution {
public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
if(l1 == null ){
return l2 ;
}else if ( l2 == null){
return l1 ;
}

ListNode dummy = new ListNode(-1);
ListNode ans = dummy ;
ListNode ptr1 = l1 ;
ListNode ptr2 = l2 ;

int carry = 0 ;

while(ptr1!=null || ptr2!=null){
int val1 = ptr1!=null? ptr1.val : 0;
int val2 = ptr2!=null? ptr2.val : 0 ;
int sum = val1 + val2 + carry ;
int d = sum%10 ;
carry = sum/10 ;

ListNode temp = new ListNode(d);

dummy.next = temp ;
dummy = dummy.next ;

ptr1 = ptr1!=null ? ptr1.next : null;
ptr2 = ptr2!=null ? ptr2.next : null;
}

if(carry>0){
ListNode temp = new ListNode(carry);
dummy.next = temp ;
dummy = dummy.next ;
}
return ans.next;
}
}
```
```