Lecture Notes on 25 Mar 2022

class Stack (object):
  def __init__(self):
    self.stack = []

  # add an item to the top of the stack
  def push (self, item):
    self.stack.append (item)

  # remove an item from the top of the stack
  def pop (self):
    return self.stack.pop()

  # check the item on the top of the stack
  def peek (self):
    return self.stack[-1]

  # check if the stack is empty
  def is_empty (self):
    return (len(self.stack) == 0)

  # return the number of elements in the stack
  def size (self):
    return (len (self.stack))

class Queue (object):
  def __init__ (self):
    self.queue = []

  # add an item to the end of the queue
  def enqueue (self, item):
    self.queue.append (item)

  # remove an item from the beginning of the queue
  def dequeue (self):
    return (self.queue.pop(0))

  # check if the queue if empty
  def is_empty (self):
    return (len(self.queue) == 0)

  # return the size of the queue
  def size (self):
    return (len(self.queue))

* Pictorial Representation of Linked Lists:
https://www.cs.utexas.edu/users/mitra/csSpring2022/cs313/notes/Singly_Linked_List.pdf

* Application of Linked Lists
  - implementation of Stacks and Queues in constant time
  - Denote connectivity of vertices in a graph - adjacency list
  - Sparse matrix representation 
  - Compact Hash Table
  - Dynamic memory allocation - linked list of free blocks

* Doubly Linked List
  - Link has now next and previous pointers
  - traverse both ways in the linked list

* Pictorial Representation
https://www.cs.utexas.edu/users/mitra/csSpring2022/cs313/notes/Doubly_Linked_List.pdf

* Circular Linked List
  - last link's next field points to the first link