India - Water

[indiakato]

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 an object that is defined by it's methods, the actual implementation is hidden.
Describe a Stack	A stack stores data in a last in first out order.
What are the 5 methods in Stack and what does each do?	1. initialize - initializes the stack class and creates new LinkedList as the stack. 2. push - adds an element to the top of the stack. 3. pop - removes the first element from the top. 4. empty - checks to see if the stack is empty. 5. to_s - converts the stack into a string.
Describe a Queue	A queue is a data structure that stores data in a first in first out order.
What are the 5 methods in Queue and what does each do?	1. initialize - initializes queue class, creates new array, sets front and back pointers to -1. 2. enqueue - adds an element to the front of the queue 3. dequeue - removes the first element in the queue. 4. front - returns the element at the front pointer of the queue. 5. empty - checks to see if the queue is empty 6. to_s - converts queue to a string
What is the difference between implementing something and using something?	Implementing something creates a class that you can use elsewhere, using something is using that class to solve a problem.

OPTIONAL JobSimulation

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

[CheezItMan]

I had a few comments on the circular buffer-Queue, and let me know what questions you have. Otherwise this is well done. Nice work.

[CheezItMan]

Suggested change

	if @front == 0 && @back == MAX_SIZE - 1 || @back == (@front - 1) % (MAX_SIZE - 1)
	raise ArgumentError
	elsif @front == -1
	@front = 0
	@back = 0
	elsif @back == MAX_SIZE - 1 && @front != 0
	@back = 0
	else
	@back += 1
	end
	@store[@back] = element
	if @front == (@back + 1) % MAX_SIZE
	raise ArgumentError, "Queue is full"
	elsif @front == -1
	@front = 0
	end
	@back = (@back + 1) % MAX_SIZE
	@store[@back] = element

[CheezItMan]

This mostly works but look at the 2nd OR condition here.

[CheezItMan]

@front is only going to be -1 if the queue is empty.

[CheezItMan]

👍

[CheezItMan]

👍

[CheezItMan]

Do you need the magic number 20.times loop? Could you instead start i at @front and keep incrementing until you hit the back?

[CheezItMan]

👍