From d8f0435c8341acf5609f872313e3cc3868d84f4e Mon Sep 17 00:00:00 2001 From: mervereis Date: Mon, 12 Oct 2026 22:12:08 +0100 Subject: [PATCH 1/3] Implement linked list with push_head, pop_tail, and remove methods --- Sprint-2/implement_linked_list/linked_list.py | 58 +++++++++++++++++++ 1 file changed, 58 insertions(+) diff --git a/Sprint-2/implement_linked_list/linked_list.py b/Sprint-2/implement_linked_list/linked_list.py index e69de29b..148ed8fc 100644 --- a/Sprint-2/implement_linked_list/linked_list.py +++ b/Sprint-2/implement_linked_list/linked_list.py @@ -0,0 +1,58 @@ + +class Node: + 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, value): + 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: + return None + + old_tail = self.tail + value = old_tail.value + + if self.head is self.tail: + self.head = None + self.tail = None + else: + self.tail = old_tail.previous + self.tail.next = None + + old_tail.next = None + old_tail.previous = None + + return value + + def remove(self, node): + if node.previous is None: + self.head = node.next + else: + node.previous.next = node.next + + if node.next is None: + self.tail = node.previous + else: + node.next.previous = node.previous + + node.next = None + node.previous = None From 9a279b4080392cc879b10d7f641a0c3fcf4c5bc6 Mon Sep 17 00:00:00 2001 From: mervereis Date: Thu, 15 Oct 2026 14:17:16 +0100 Subject: [PATCH 2/3] Refactor Node and LinkedList classes for type hinting and improved readability --- Sprint-2/implement_linked_list/linked_list.py | 25 +++++++++++-------- 1 file changed, 15 insertions(+), 10 deletions(-) diff --git a/Sprint-2/implement_linked_list/linked_list.py b/Sprint-2/implement_linked_list/linked_list.py index 148ed8fc..36384b07 100644 --- a/Sprint-2/implement_linked_list/linked_list.py +++ b/Sprint-2/implement_linked_list/linked_list.py @@ -1,17 +1,22 @@ +from typing import Optional + + class Node: - def __init__(self, value): - self.value = value - self.next = None - self.previous = None + __slots__ = ("value", "next", "previous") + + def __init__(self, value: object) -> None: + self.value: object = value + self.next: Optional["Node"] = None + self.previous: Optional["Node"] = None class LinkedList: - def __init__(self): - self.head = None - self.tail = None + def __init__(self) -> None: + self.head: Optional[Node] = None + self.tail: Optional[Node] = None - def push_head(self, value): + def push_head(self, value: object) -> Node: new_node = Node(value) if self.head is None: @@ -24,7 +29,7 @@ def push_head(self, value): return new_node - def pop_tail(self): + def pop_tail(self) -> Optional[object]: if self.tail is None: return None @@ -43,7 +48,7 @@ def pop_tail(self): return value - def remove(self, node): + def remove(self, node: Node) -> None: if node.previous is None: self.head = node.next else: From c4af62cb8cbecb26bedcb156df44123aae69a5ab Mon Sep 17 00:00:00 2001 From: mervereis Date: Thu, 15 Oct 2026 14:26:07 +0100 Subject: [PATCH 3/3] Refactor pop_tail method to streamline tail removal logic --- Sprint-2/implement_linked_list/linked_list.py | 11 +---------- 1 file changed, 1 insertion(+), 10 deletions(-) diff --git a/Sprint-2/implement_linked_list/linked_list.py b/Sprint-2/implement_linked_list/linked_list.py index 36384b07..4e1754a3 100644 --- a/Sprint-2/implement_linked_list/linked_list.py +++ b/Sprint-2/implement_linked_list/linked_list.py @@ -35,16 +35,7 @@ def pop_tail(self) -> Optional[object]: old_tail = self.tail value = old_tail.value - - if self.head is self.tail: - self.head = None - self.tail = None - else: - self.tail = old_tail.previous - self.tail.next = None - - old_tail.next = None - old_tail.previous = None + self.remove(old_tail) return value