Branches - Kelsey

[kelsk]

Stacks and Queues

Thanks for doing some brain yoga. You are now submitting this assignment!

Comprehension Questions

Question	Answer
What is an ADT?	An Abstract Data Type is any data type that can be implemented any way, as long as it can perform the operations in its type description.
Describe a Stack	A stack is a last-in, first-out abstract data type.
What are the 5 methods in Stack and what does each do?	A Stack can perform these operations - push: adds an element to the stack, pop: removes the last item from the stack, empty: checks whether the stack is empty, to_s: returns a string of the array, initialize: initializes.
Describe a Queue	A queue is a first-in, first-out data type, which can be maintained with a circular buffer.
What are the 5 methods in Queue and what does each do?	Enqueue: adds an item to the queue, dequeue: removes the first item from the queue, empty: checks whether the queue is empty, front: returns the value at the front of the queue, size: returns the length of the queue, to_s: returns a string of the array without the nils.
What is the difference between implementing something and using something?	Implementation is initializing a class, setting up a data structure and methods, so that it is able to be used. Using something is calling the implementation and running the methods.

OPTIONAL JobSimulation

Question	Answer
Did you include a sample run of your code as a comment?

[CheezItMan]

Some issues with the Queue class. Take a look at my comments and let me know if you have any questions. The other parts seem to work well.

[CheezItMan]

👍

[CheezItMan]

Suggested change

	if stack.empty?
	return true
	else
	return false
	end
	return stack.empty?

[CheezItMan]

You need to make sure the front will wrap around the queue

Suggested change

	@front = @front+1
	@front = (@front+1) % @store.length

You also need to check to see if the queue is empty!

[CheezItMan]

This works, but it's not very efficient.

[CheezItMan]

This compacts the buffer which removes any extra space you have in the buffer, which you might need in the Queue!

Better to do something like this:

    return "[]" if @front == -1
    current = @front
    output = "["
    next = (@front + 1) % @store.length
    while next != @back
      output += "#{@store[current]},"
      current = (current + 1) % @store.length
      next = (next + 1) % @store.length
    end

    output += "#{@store[current]}]"
    return output