编辑代码

/**
 * Definition for singly-linked list.
 * class ListNode {
 *   int val;
 *   ListNode? next;
 *   ListNode([this.val = 0, this.next]);
 * }
 */
class Solution {
  ListNode? addTwoNumbers(ListNode? l1, ListNode? l2) {
      ListNode rs = ListNode();
      
  }
}

void main() {
  print('Hello world!     - dart.jsrun.net');
}