Glasgow | 26-Jul-SDC | Shreef Ibrahim | Sprint 2 | Implement a linked list

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