Lecture Notes on 26 Oct 2022

class Link (object):
  def __init__ (self, data, next = None):
    self.data = data
    self.next = next

class LinkedList (object):
  # initialize an empty Linked List
  def __init__ (self):
    self.first = None

  # add an item to the beginning of the list
  def insert_first (self, data):
    new_link = Link (data)

    new_link.next = self.first
    self.first = new_link

  # add an item to the end of the list
  def insert_last (self, data):
    new_link = Link (data)

    current = self.first

    if (current == None):
      self.first = new_link
      return

    while (current.next != None):
      current = current.next

    current.next = new_link

  # find an item in the LinkedList
  def find_link (self, data):
    current = self.first

    if (current == None):
      return None

    while (current.data != data):
      if (current.next == None):
        return None
      else:
        current = current.next

    return current

  # delete a link with a given data
  def delete_link (self, data):
    previous = self.first
    current = self.first

    if (current == None):
      return None

    while (current.data != data):
      if (current.next == None):
        return None
      else:
        previous = current
        current = current.next

    if (current == self.first):
      self.first = current.next
    else:
      previous.next = current.next

    return current