/**

* Definition for singly-linked list.

* public class ListNode {

* int val;

* ListNode next;

* ListNode(int x) { val = x; }

* }

*/

public class Solution {

public ListNode addTwoNumbers(ListNode l1, ListNode l2) {

if (l1 == null)

return l2;

if (l2 == null)

return l1;

int sum = l1.val + l2.val;

int carry = sum / 10;

sum %= 10;

ListNode resultHead = new ListNode(sum);

ListNode curr = resultHead;

l1 = l1.next;

l2 = l2.next;

while (l1 != null && l2 != null) {

sum = l1.val + l2.val + carry;

carry = sum / 10;

sum %= 10;

curr.next = new ListNode(sum);

curr = curr.next;

l1 = l1.next;

l2 = l2.next;

}

while (l1 != null) {

sum = l1.val + carry;

carry = sum / 10;

sum %= 10;

curr.next = new ListNode(sum);

curr = curr.next;

l1 = l1.next;

}

while (l2 != null) {

sum = l2.val + carry;

carry = sum / 10;

sum %= 10;

curr.next = new ListNode(sum);

curr = curr.next;

l2 = l2.next;

}

if (carry != 0) {

curr.next = new ListNode(carry);

curr = curr.next;

}

return resultHead;

}

}