current.next = l1 l1 = l1.next else: current.next = l2 l2 = l2.next current = current.next current.next = l1 if l1 else l2 return dummyHead.next return l1 or l2 if __name__ == '__main__': list_1 = ListNode.buildSortedList(2) list_2 = ListNode.buildSortedList(3) ListNode.show(list_1) ListNode.show(list_2) solution = Solution() merged = solution.mergeTwoLists(list_1, list_2) ListNode.show(merged) # list_1 = ListNode.buildEmptyList() # list_2 = ListNode.buildSortedList(1) # ListNode.show(list_1) # ListNode.show(list_2) # solution = Solution() # merged = solution.mergeTwoListsRefine(list_1, list_2)