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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.

Solution:

```class Solution {
public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
ListNode result = new ListNode(0);
ListNode p1 = l1;
ListNode p2 = l2;
ListNode curr = result;
int carry=0;
while(p1!=null || p2!=null)
{
int x = (p1!=null)?p1.val:0;
int y = (p2!=null)?p2.val:0;
int sum = carry+x+y;
carry = sum/10;
curr.next = new ListNode(sum%10);
curr=curr.next;
if(p1!=null) p1=p1.next;
if(p2!=null) p2=p2.next;
}
if(carry>0)
{
curr.next = new ListNode(carry);
}
return result.next;
}
}
```