Çift Uçlu Kuyruk (Deque)

class Deque:
    """Circular buffer: both ends wrap around, so nothing is ever shifted.

    (The standard library already has one: collections.deque.)
    """

    def __init__(self, capacity: int) -> None:
        self._items = [0] * capacity
        self._front = 0
        self._size = 0

    def push_front(self, value: int) -> None:
        if self._size == len(self._items):
            raise OverflowError("deque is full")
        self._front = (self._front - 1) % len(self._items)
        self._items[self._front] = value
        self._size += 1

    def push_back(self, value: int) -> None:
        if self._size == len(self._items):
            raise OverflowError("deque is full")
        self._items[(self._front + self._size) % len(self._items)] = value
        self._size += 1

    def pop_front(self) -> int:
        if self._size == 0:
            raise IndexError("deque is empty")
        value = self._items[self._front]
        self._front = (self._front + 1) % len(self._items)
        self._size -= 1
        return value

    def pop_back(self) -> int:
        if self._size == 0:
            raise IndexError("deque is empty")
        self._size -= 1
        return self._items[(self._front + self._size) % len(self._items)]

    def __len__(self) -> int:
        return self._size


d = Deque(8)
d.push_back(1)
d.push_back(2)
d.push_front(0)       # [0, 1, 2]
print(d.pop_back())   # 2
print(d.pop_front())  # 0
print(len(d))         # 1