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.

Example

```Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8
Explanation: 342 + 465 = 807.```

```/**
* public class ListNode {
*     int val;
*     ListNode next;
*     ListNode(int x) { val = x; }
* }
*/
class Solution {
public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
}
}```

`class Solution {    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {        int num1, num2, num0;        ListNode l = null;        if (l1 != null && l2 != null &&                l1.next != null && l2.next != null &&                l1.next.next != null && l2.next.next != null) {            num1 = l1.val + l1.next.val * 10 + l1.next.next.val * 100;            num2 = l2.val + l2.next.val * 10 + l2.next.next.val * 100;            num0 = num1 + num2;            l = new ListNode(num0 % 10);            l.next = new ListNode((num0 / 10) % 10);            l.next.next = new ListNode(num0 / 100);        }        return l;    }}`

`class Solution {    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {        int num1 = 0, num2 = 0, num0;        int i = 0;        while (l1 != null) {            num1 += l1.val * Math.pow(10, i);            i++;            l1 = l1.next;        }        int j = 0;        while (l2 != null) {            num2 += l2.val * Math.pow(10, j);            j++;            l2 = l2.next;        }        num0 = num1 + num2;        ListNode l = null;        l = new ListNode(num0 % 10);        l.next = new ListNode((num0 / 10) % 10);        l.next.next = new ListNode(num0 / 100);        return l;    }}`

```9 / 1562 test cases passed.
Submitted: 0 minutes ago
Input:
[0]
[0]
Output:
[0,0,0]
Expected:
[0]```

`class Solution {    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {        int num1 = 0, num2 = 0, num0;        int i = 0;        while (l1 != null) {            num1 += l1.val * Math.pow(10, i);            i++;            l1 = l1.next;        }        int j = 0;        while (l2 != null) {            num2 += l2.val * Math.pow(10, j);            j++;            l2 = l2.next;        }        num0 = num1 + num2;        ListNode l = null;        if (num0 == 0) {            l = new ListNode(0);        } else {            l = new ListNode(num0 % 10);            l.next = new ListNode((num0 / 10) % 10);            l.next.next = new ListNode(num0 / 100);        }        return l;    }}`

```10 / 1562 test cases passed.
Submitted: 0 minutes ago
Input:
[0]
[1]
Output:
[1,0,0]
Expected:
[1]```

`class Solution {    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {        int num1 = 0, num2 = 0, num0;        int i = 0;        while (l1 != null) {            num1 += l1.val * Math.pow(10, i);            i++;            l1 = l1.next;        }        int j = 0;        while (l2 != null) {            num2 += l2.val * Math.pow(10, j);            j++;            l2 = l2.next;        }        num0 = num1 + num2;        ListNode l = new ListNode(0);        ListNode head = l;        while (num0 != 0) {            l.val = num0 % 10;            num0 /= 10;            if (num0 != 0) {                l.next = new ListNode(0);                l = l.next;            } else {                l.next = null;            }        }        return head;    }}`

```787 / 1562 test cases passed.
Submitted: 0 minutes ago
Input:
[9]
[1,9,9,9,9,9,9,9,9,9]
Output:
[0,-4,-6,-3,-8,-4,-7,-4,-1,-2]
Expected:
[0,0,0,0,0,0,0,0,0,0,1]```

`class Solution {    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {        ListNode l = new ListNode(0);        ListNode head = l;        int sum = 0, tmp = 0;        //l1     : 9 9        //l2     : 1 9 9 9        //l.next : 0 9 0 0 1        while (l1 != null && l2 != null) {            sum = l1.val + l2.val + tmp;            l.next = new ListNode(sum % 10);            tmp = sum / 10;            l = l.next;            l1 = l1.next;            l2 = l2.next;        }        while (l2 != null) {            sum = l2.val + tmp;            l.next = new ListNode(sum % 10);            tmp = sum / 10;            l = l.next;            l2 = l2.next;        }        while (l1 != null) {            sum =l1.val + tmp;            l.next = new ListNode(sum % 10);            tmp = sum / 10;            l = l.next;            l1 = l1.next;        }        if (tmp == 1) {            l.next = new ListNode(tmp);        }        return head.next;    }}`

```Submission Detail
1562 / 1562 test cases passed.
Status: Accepted
Runtime: 69 ms
Submitted: 0 minutes ago```

`class Solution {    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {        if (l1 == null || l2 == null) {            return l1 == null ? l2 : l1;        }        int value = l1.val + l2.val;        ListNode result = new ListNode(value % 10);        result.next = addTwoNumbers(l1.next, l2.next);        if (value >= 10) {            result.next = addTwoNumbers(new ListNode(value / 10), result.next);        }        return result;    }}`