function addInList(head1, head2) { let l1 = [], l2 = [], l3 = [] let cur = head1 while (cur) { l1.push(cur.val) cur = cur.next } cur = head2 while (cur) { l2.push(cur.val) cur = cur.next } l3 = add(l1, l2) let dummy = new ListNode(0...