London | 26-SDC-Mar | Jamal Laqdiem| Sprint 2 | implement a linked list in py

Sprint-2/implement_linked_list/linked_list.py

@@ -0,0 +1,62 @@
+from dataclasses import dataclass
+from typing import Any, Optional
+# to reduce memory usage we use slots true to tells Python not to create a dynamic __dict__ for every node,
+@dataclass(slots=True)
+class Node:
+    value: Any
+    next: Optional['Node'] = None
+    previous: Optional['Node'] = None
+
+
+class LinkedList:
+    def __init__(self) -> None:
+        self.head: Optional[Node] = None
+        self.tail: Optional[Node] = None
+
+    def push_head(self, value: Any) -> Node:
+        new_node = Node(value)
+
+        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) -> Optional[Any]:
+        if not self.tail:
+            return None
+
+        value_to_return = self.tail.value
+        self.remove(self.tail)
+        return value_to_return
+
+    def remove(self, node: Node) -> None:
+        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:
+            assert node.previous is not None
+            assert node.next is not None
+            node.previous.next = node.next
+            node.next.previous = node.previous
+
+        node.next = None
+        node.previous = None