[LeetCode]Add Two Numbers

public class Solution {
    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        int carry = 0;
        ListNode result = new ListNode(0);
        ListNode p = result;
        while (l1 != null && l2 != null) {
            int tmp = l1.val + l2.val + carry;
            carry = tmp > 9 ? 1 : 0;
            tmp = tmp > 9 ? tmp - 10 : tmp;
            p.next = new ListNode(tmp);
            p = p.next;
            l1 = l1.next;
            l2 = l2.next;
        }
        if (l1 == null && l2 == null) {
            if (carry != 0)
                p.next = new ListNode(carry);
        } else if (carry == 0) {
            p.next = l1 == null ? l2 : l1;
        } else {
            ListNode l = l1 == null ? l2 : l1;
            p.next = addTwoNumbers(l, new ListNode(carry));
        }
        return result.next;
    }
}