class ListNode: def __init__(self, val=0, next=None): self.val = val self.next = next def addTwoNumbers(l1: ListNode, l2: ListNode) -> ListNode: dummy = ListNode() curr = dummy carry = 0 while l1 or l2 or carry: sum_val = carry if l1: sum_val += l1.val l1 = l1.next if l2: sum_val += l2.val l2 = l2.next carry, val = divmod(sum_val, 10) curr.next = ListNode(val) curr = curr.next return dummy.next