diff --git a/Sprint-2/implement_linked_list/linked_list.py b/Sprint-2/implement_linked_list/linked_list.py index e69de29b..7aca75bc 100644 --- a/Sprint-2/implement_linked_list/linked_list.py +++ b/Sprint-2/implement_linked_list/linked_list.py @@ -0,0 +1,56 @@ + +from __future__ import annotations + +from typing import Generic, TypeVar + +T = TypeVar("T") + + +class Node(Generic[T]): + __slots__ = ("value", "next", "previous") + + def __init__(self, value: T) -> None: + self.value: T = value + self.next: Node[T] | None = None + self.previous: Node[T] | None = None + + +class LinkedList(Generic[T]): + def __init__(self) -> None: + self.head: Node[T] | None = None + self.tail: Node[T] | None = None + + def push_head(self, value: T) -> Node[T]: + new_node = Node(value) + + if self.head is None: + self.head = new_node + self.tail = new_node + else: + new_node.next = self.head + self.head.previous = new_node + self.head = new_node + + return new_node + + def pop_tail(self) -> T | None: + if self.tail is None: + return None + + value = self.tail.value + self.remove(self.tail) + return value + + def remove(self, node: Node[T]) -> None: + if node.previous is not None: + node.previous.next = node.next + else: + self.head = node.next + + if node.next is not None: + node.next.previous = node.previous + else: + self.tail = node.previous + + node.next = None + node.previous = None