Leetcode#2||Add Two Numbers

/**
* 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 && l2 == null) {
return null;
} else if (l1 == null) {
return l2;
} else if (l2 == null) {
return l1;
}

ListNode dummy = new ListNode(-1);
ListNode ptr = dummy;
int carry = 0;

while (l1 != null && l2 != null) {
int val = l1.val + l2.val + carry;
carry = val / 10;
val = val % 10;
ptr.next = new ListNode(val);
ptr = ptr.next;
l1 = l1.next;
l2 = l2.next;
}

ListNode tempPtr = (l1 == null) ? l2 : l1;

while (tempPtr != null) {
int val = tempPtr.val + carry;
carry = val / 10;
val = val % 10;
ptr.next = new ListNode(val);
ptr = ptr.next;
tempPtr = tempPtr.next;
}

if (carry == 1) {
ptr.next = new ListNode(1);
}

return dummy.next;
}
}