Data structures and algorithms lab4

Data structures and algorithms lab4

• 1.
  DATA STRUCTURES ANDALGORITHMS LAB 4 Bianca Tesila FILS, March 2014
• 2.
  OBJECTIVES Queue  Queue vsstack  Applications 
• 3.
  QUEUES  instance of anabstract data type (ADT) that formalizes the concept of restricted collection (FIFO = first in first out)
• 4.
  QUEUES: BASIC OPERATIONS  enqueue(x)   dequeue()    Removesthe element from the head of the queue and returns it Returns an error if the stack is empty peek()   Adds the element x at the tail of the queue Returns (but does not remove) the element at the head of the queue isEmpty()  Returns 1 if the queue is empty and 0 otherwise
• 5.
  QUEUES: IMPLEMENTATION   with astatic data structure (array, circular array) with a dynamic data structure (list) ‼Short reminder: Why do we use circular arrays instead of simple arrays?
• 6.
  QUEUES: WITH SIMPLEARRAYS
• 7.
  QUEUES: WITH CIRCULARARRAYS
• 8.
  QUEUES VS STACKS ‼Exercise: Implementa stack using 2 queues. The corresponding class is QueuedStack and has the following methods:  an empty constructor  destructor  push  pop There are several solutions for this task. Using a similar approach, implement a queue using 2 stacks: StackedQueue.
• 9.
  QUEUES AND STACKS:APPLICATIONS ‼Exercise: Implement a stack which provides an efficient get minimum function along with regular push and pop functionality. Hint: use an auxiliary stack. Taking into consideration that a queue can be implemented using 2 stacks, use a similar approach for getting the minimum element out of a queue.
• 10.
  HOMEWORK o Finish all thelab exercises. o Implement a messaging system using queues.   Messages are received in the order they are sent You should use the following classes:        Message MessageSender MessageReceiver A Message object has a sender, recipient, content (make an array of chars!!) and a date A Message is placed in a queue by a MessageSender object A Message is removed from a queue by a MessageReceiver object, which can also display the content of the message. Your queue class can receive any types of objects, including Message Objects