from abc import ABC, abstractmethod
class Sequence(ABC):
@abstractmethod
def append(self, item):
pass
@abstractmethod
def get(self, index):
pass
@abstractmethod
def length(self):
pass
@abstractmethod
def __iter__(self):
pass
def is_empty(self):
return self.length() == 0
class ListSequence(Sequence):
def __init__(self):
self._data = []
def append(self, item):
self._data.append(item)
def get(self, index):
return self._data[index]
def length(self):
return len(self._data)
def __iter__(self):
return iter(self._data)
class Node:
def __init__(self, value):
self.value = value
self.next = None
class LinkedListSequence(Sequence):
def __init__(self):
self._head = None
self._size = 0
def append(self, item):
new_node = Node(item)
if self._head is None:
self._head = new_node
else:
current = self._head
while current.next:
current = current.next
current.next = new_node
self._size += 1
def get(self, index):
if index < 0 or index >= self._size:
raise IndexError("index out of range")
current = self._head
for _ in range(index):
current = current.next
return current.value
def length(self):
return self._size
def __iter__(self):
current = self._head
while current:
yield current.value
current = current.next
