[LeetCode]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 ((null == l1) && (null == l2)) {
return null;
}

ListNode result = null;
ListNode node = null;
int carry = 0;
while ((null != l1) && (null != l2)) {
int value = l1.val + l2.val + carry;
carry = value / 10;
value = value % 10;
if (null == node) {
result = new ListNode(value);
node = result;
} else {
node.next = new ListNode(value);
node = node.next;
}

l1 = l1.next;
l2 = l2.next;
}

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

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

if (0 != carry) {
node.next = new ListNode(carry);
node = node.next;
}

return result;
}
}