diff --git a/Sprint-2/implement_linked_list/linked_list.py b/Sprint-2/implement_linked_list/linked_list.py index e69de29..e15fff6 100644 --- a/Sprint-2/implement_linked_list/linked_list.py +++ b/Sprint-2/implement_linked_list/linked_list.py @@ -0,0 +1,67 @@ +from typing import Optional, Iterator + + +class Node: + + def __init__(self, value): + self.value = value + self.next: Optional["Node"] = None + self.previous: Optional["Node"] = None + + +class LinkedList: + def __init__(self): + self.head: Optional[Node] = None + self.tail: Optional[Node] = None + + def push_head(self, value) -> Node: + 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): + if self.tail is None: + raise IndexError("pop_tail from empty linked list") + + value = self.tail.value + self.remove(self.tail) + return value + + def remove(self, node: Node): + if node is None: + raise ValueError("Cannot remove None node") + + if node == self.head == self.tail: + self.head = None + self.tail = None + elif node == self.head: + self.head = node.next + if self.head: + self.head.previous = None + elif node == self.tail: + self.tail = node.previous + if self.tail: + self.tail.next = None + else: + node.previous.next = node.next + node.next.previous = node.previous + + node.next = None + node.previous = None + + def __iter__(self) -> Iterator: + current = self.head + while current: + yield current.value + current = current.next + + def __repr__(self) -> str: + return f"LinkedList([{', '.join(str(v) for v in self)}])" \ No newline at end of file