diff --git a/Sprint-2/implement_linked_list/linked_list.py b/Sprint-2/implement_linked_list/linked_list.py index e69de29b..5ce66e2d 100644 --- a/Sprint-2/implement_linked_list/linked_list.py +++ b/Sprint-2/implement_linked_list/linked_list.py @@ -0,0 +1,62 @@ +class Node: + __slots__ = ("value", "next", "previous") + + def __init__(self, value): + self.value = value + self.next = None + self.previous = None + + +class LinkedList: + def __init__(self): + self.head = None + self.tail = None + + def push_head(self, item): + new_node = Node(item) + + if not self.head: + 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 not self.tail: + return None + + popped_node = self.tail + value = popped_node.value + + self.remove(popped_node) + + return value + + def remove(self, node: Node): + if not node: + return + + if node == self.head: + self.head = node.next + if self.head: + self.head.previous = None + else: + self.tail = None + + elif node == self.tail: + self.tail = node.previous + if self.tail: + self.tail.next = None + else: + self.head = None + + else: + node.previous.next = node.next + node.next.previous = node.previous + + node.next = None + node.previous = None \ No newline at end of file