# Add Two Numbers as Lists

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

```    342 + 465 = 807
```
Make sure there are no trailing zeros in the output list
So, 7 -> 0 -> 8 -> 0 is not a valid response even though the value is still 807.

Solution:

Time: O(n)
Space: O(n)

/**
* Definition for singly-linked list.
* class ListNode {
*     public int val;
*     public ListNode next;
*     ListNode(int x) { val = x; next = null; }
* }
*/
public class Solution {
public ListNode addTwoNumbers(ListNode A, ListNode B) {
ListNode dummy = new ListNode(0);
ListNode p = dummy;
int carry = 0;
while (A != null && B != null) {
ListNode node = new ListNode(0);
int val = A.val + B.val + carry;
node.val = val % 10;
carry = val / 10;
A = A.next;
B = B.next;
p.next = node;
p = p.next;
}
while (A != null) {
ListNode node = new ListNode(0);
int val = A.val + carry;
node.val = val % 10;
carry = val / 10;
A = A.next;
p.next = node;
p = p.next;
}
while (B != null) {
ListNode node = new ListNode(0);
int val = B.val + carry;
node.val = val % 10;
carry = val / 10;
B = B.next;
p.next = node;
p = p.next;
}
if (carry != 0) {
p.next = new ListNode(1);
}
return dummy.next;
}
}