LeetCode-AddTwoNumbers

// https://leetcode.com/problems/add-two-numbers/submissions/
public class Solution {
    public ListNode AddTwoNumbers(ListNode l1, ListNode l2) {
        ListNode head = null;
        ListNode current = null;
        int carry = 0;
        
        while(l1 != null || l2 != null) {
                        
            var v1 = (l1?.val) ?? 0;
            var v2 = (l2?.val) ?? 0;
            var total = v1 + v2 + carry;
            
            int t1 = total % 10;
            var node = new ListNode(t1);
            carry = total / 10;
            
            if(current != null) {
                current.next = node;
            }

            current = node;
            
            if(head == null) {
                head = node;
            }
                        
            l1 = l1?.next;
            l2 = l2?.next;
        }
        
        if(carry > 0) {
            current.next = new ListNode(carry);
        }
        
        return head;
    }
}