Added adding operations on DoublyLL

Author: shreyasvedpathak

Linked List/doublyLL.py

@@ -0,0 +1,145 @@
+import os
+from typing import NewType, Sized
+
+class _Node:
+__slots__ = '_element', '_link', '_prev'
+def __init__(self, element, link, prev):
+self._element = element
+self._link = link
+self._prev = prev
+
+class DoublyLL:
+def __init__(self):
+self._head = None
+self._tail = None
+self._size = 0
+
+def __len__(self):
+return self._size
+
+def isempty(self):
+return self._size == 0
+
+def addLast(self, e):
+newest = _Node(e, None, None)
+
+if self.isempty():
+self._head = newest
+else:
+self._tail._link = newest
+newest._prev = self._tail
+self._tail = newest
+self._size += 1
+
+def addFirst(self, e):
+newest = _Node(e, None, None)
+
+if self.isempty():
+self._head = newest
+self._tail = newest
+else:
+newest._link = self._head
+self._head._prev = newest
+self._head = newest
+self._size += 1
+
+def addAnywhere(self, e, index):
+if index >= self._size:
+print(f'Index value out of range, it should be between 0 - {self._size - 1}')
+elif self.isempty():
+print("List was empty, item will be added at the end")
+self.addLast(e)
+elif index == 0:
+self.addFirst(e)
+elif index == self._size - 1:
+self.addLast(e)
+else:
+newest = _Node(e, None, None)
+p = self._head
+for _ in range(index - 1):
+p = p._link
+newest._link = p._link
+p._link._prev = newest
+newest._prev = p
+p._link = newest
+self._size += 1
+
+
+def display(self):
+if self.isempty():
+print("List is Empty")
+return
+
+p = self._head
+print("NULL<-->", end='')
+while p:
+print(p._element, end="<-->")
+p = p._link
+print("NULL")
+print(
+f"Head : {self._head._element}, Tail : {self._tail._element}")
+
+###############################################################################
+
+def options():
+'''
+Prints Menu for operations
+'''
+options_list = ['Add Last', 'Add First', 'Add Anywhere',
+'Remove First', 'Remove Last', 'Remove Anywhere',
+'Display List', 'Exit']
+
+print("MENU")
+for i, option in enumerate(options_list):
+print(f'{i + 1}. {option}')
+
+choice = int(input("Enter choice: "))
+return choice
+
+
+def switch_case(choice):
+'''
+Switch Case for operations
+'''
+os.system('cls')
+if choice == 1:
+elem = int(input("Enter Item: "))
+DL.addLast(elem)
+print("Added Item at Last!\n\n")
+
+elif choice == 2:
+elem = int(input("Enter Item: "))
+DL.addFirst(elem)
+print("Added Item at First!\n\n")
+
+elif choice == 3:
+elem = int(input("Enter Item: "))
+index = int(input("Enter Index: "))
+DL.addAnywhere(elem, index)
+
+elif choice == 4:
+print("Removed Element from First:", DL.removeFirst())
+
+elif choice == 5:
+print("Removed Element from last:", DL.removeLast())
+
+elif choice == 6:
+index = int(input("Enter Index: "))
+print(f"Removed Item: {DL.removeAnywhere(index)} !\n\n")
+
+elif choice == 7:
+print("List: ", end='')
+DL.display()
+print("\n")
+
+elif choice == 8:
+import sys
+sys.exit()
+
+###############################################################################
+
+
+DL = DoublyLL()
+while True:
+choice = options()
+switch_case(choice)