Added non-interactive DLL

README.md

@@ -22,6 +22,7 @@ A repo for storing Python code and tracking learning progress. All programs are
 │   ├── taskgroup_error_handling.py
 │   └── worker_pipeline.py
 └── data_structures
+    ├── doubly_linked_list-interactive.py
     ├── doubly_linked_list.py
     └── singly_linked_list.py
 ```

data_structures/doubly_linked_list-interactive.py

@@ -0,0 +1,171 @@
+"""A doubly linked list implementation with an interactive command-line menu."""
+
+
+from dataclasses import dataclass
+import os
+
+
+@dataclass
+class Node:
+    data: int
+    prev: "Node | None" = None
+    next: "Node | None" = None
+
+
+class DoublyLinkedList:
+    def __init__(self, items: list[int]) -> None:
+        self.head: Node | None = None
+        self.tail: Node | None = None
+        current: Node | None = None
+        for item in items:
+            new_node = Node(item)
+            if current is None:
+                self.head = new_node
+            else:
+                current.next = new_node
+                new_node.prev = current
+            current = new_node
+        self.tail = current
+
+    def append(self, item: int) -> None:
+        new_node = Node(item)
+        if self.head is None:
+            self.head = new_node
+            self.tail = new_node
+            return
+        assert self.tail is not None
+        new_node.prev = self.tail
+        self.tail.next = new_node
+        self.tail = new_node
+
+    def fetch_reversed_list(self) -> str:
+        if self.head is None:
+            return "(empty)"
+        current = self.tail
+        values: list[str] = []
+        while current is not None:
+            values.append(str(current.data))
+            current = current.prev
+        return " ".join(values)
+
+    def __len__(self) -> int:
+        size = 0
+        current = self.head
+        while current is not None:
+            size += 1
+            current = current.next
+        return size
+
+    def print_list(self) -> None:
+        if self.head is None:
+            print("(empty)")
+            return
+        current = self.head
+        values: list[str] = []
+        while current is not None:
+            values.append(str(current.data))
+            current = current.next
+        print(" ".join(values))
+
+    def remove(self, item: int) -> bool:
+        if self.head is None:
+            return False
+        if self.head.data == item:
+            self.head = self.head.next
+            if self.head is None:
+                self.tail = None
+            else:
+                self.head.prev = None
+            return True
+        current = self.head
+        while current.next is not None:
+            if current.next.data == item:
+                removed_node = current.next
+                current.next = removed_node.next
+                if removed_node.next is not None:
+                    removed_node.next.prev = current
+                if removed_node is self.tail:
+                    self.tail = current
+                return True
+            current = current.next
+        return False
+
+    def sort_list(self) -> None:
+        values: list[int] = []
+        current = self.head
+        while current is not None:
+            values.append(current.data)
+            current = current.next
+        values.sort()
+        sorted_list = DoublyLinkedList(values)
+        self.head = sorted_list.head
+        self.tail = sorted_list.tail
+
+
+def clear_screen() -> None:
+    os.system("cls" if os.name == "nt" else "clear")
+
+
+def command_loop(linked_list: DoublyLinkedList) -> None:
+    clear_screen()
+    while True:
+        print("Current list: ", end="")
+        linked_list.print_list()
+        print("____________________")
+        command = input(
+            "Command options:\n"
+            "    1  append item\n"
+            "    2  remove item\n"
+            "    3  count items\n"
+            "    4  sort list\n"
+            "    5  print reverse\n"
+            "    6  exit\n"
+            "____________________\n"
+            "Command: ")
+
+        if command == "1":
+            try:
+                item = int(input("\nEnter item to append: "))
+                linked_list.append(item)
+            except ValueError:
+                input(" - Please enter a valid integer. Press Enter to continue.")
+
+        elif command == "2":
+            try:
+                item = int(input("\nEnter item to remove: "))
+                removed = linked_list.remove(item)
+                if not removed:
+                    input(" - No matching item found.\n - Press Enter to continue.")
+            except ValueError:
+                input(" - Please enter a valid integer.\n - Press Enter to continue.")
+
+        elif command == "3":
+            size = len(linked_list)
+            word = "item" if size == 1 else "items"
+            input(f"\n - The list contains {size} {word}.\n - Press Enter to continue.")
+
+        elif command == "4":
+            linked_list.sort_list()
+
+        elif command == "5":
+            reversed_list = linked_list.fetch_reversed_list()
+            input(f"\n - Reversed list: {reversed_list}\n - Press Enter to continue.")
+
+        elif command == "6":
+            print("\n - Goodbye!\n")
+            break
+
+        else:
+            input(" - Invalid command.\n - Press Enter to continue.")
+
+        clear_screen()
+
+
+def main() -> None:
+    numbers = [4, 2, 7, 1, 9, 6, 5, 8, 3]
+    linked_list = DoublyLinkedList(numbers)
+    command_loop(linked_list)
+
+
+if __name__ == "__main__":
+    main()