ZA | 25-SDC-July | Luke Manyamazi | Sprint 2 | Implement-Linked_List

.gitignore

@@ -1,4 +1,4 @@
 .DS_Store
 node_modules
-.venv
+venv
 __pycache__

Sprint-2/implement_linked_list/linked_list.py

@@ -0,0 +1,65 @@
+class LinkedList:
+    class Node:
+        def __init__(self, value):
+            self.value = value
+            self.next = None
+            self.previous = None
+
+    def __init__(self):
+        self.head = None
+        self.tail = None
+
+    def push_head(self, value):
+        """Add an element to the start of the list. Returns a handle to the node."""
+        new_node = self.Node(value)
+
+        if self.head is None:
+            # List is empty
+            self.head = new_node
+            self.tail = new_node
+        else:
+            # Add to front
+            new_node.next = self.head
+            self.head.previous = new_node
+            self.head = new_node
+
+        return new_node
+
+    def pop_tail(self):
+        """Remove and return the element from the end of the list."""
+        if self.tail is None:
+            raise IndexError("pop from empty list")
+
+        value = self.tail.value
+
+        if self.head == self.tail:
+            # Only one element
+            self.head = None
+            self.tail = None
+        else:
+            # Multiple elements
+            self.tail = self.tail.previous
+            self.tail.next = None
+
+        return value
+
+    def remove(self, node):
+        """Remove a specific node from the list using the handle from push_head."""
+        if node is None:
+            return
+
+        if node.previous is not None:
+            node.previous.next = node.next
+        else:
+            # node is head
+            self.head = node.next
+
+        if node.next is not None:
+            node.next.previous = node.previous
+        else:
+            # node is tail
+            self.tail = node.previous
+
+        # Clean up references
+        node.next = None
+        node.previous = None