Water - Beatrice #25

Beatress · 2021-04-24T19:53:52Z

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 a data type that hides its internal working through encapsulation. It is often based off of primitive datatypes
Describe a Stack	A stock is like a pile of books that can only be manipulated from the top. It operates on a last in first out model
What are the 5 methods in Stack and what does each do?	Push puts an item on the top of the stack. Pop takes an item and returns it off the top of the stack. Then there is a method to check if the stack is empty
Describe a Queue	A queue is like a line of people. Items are added to the back and leave from the front. This means that it operates on a first in first out model
What are the 5 methods in Queue and what does each do?	A queue has methods to enqueue, putting an element at the end, dequeue, taking an element from the beginning of the queue, check if it is empty, peek at the first element, and return the length
What is the difference between implementing something and using something?	When you implement something you have to be concerned with all of the details, but when you use something you just have to worry about how it is used

OPTIONAL JobSimulation

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

CheezItMan

Nice work Beatrice, you hit the main learning goals here. Well done.

CheezItMan · 2021-04-28T00:29:47Z

lib/queue.rb

+   if @front == (@back + 1) % @size
+      self.expand
+    end


This defeats the circular nature of the list, so that you can work with a fixed size, but it does let you resize the buffer.

CheezItMan · 2021-04-28T00:29:54Z

lib/queue.rb

+    @size = 10
+    @store = Array.new(@size)
+    @front = 0
+    @back = 0
  end

  def enqueue(element)


CheezItMan · 2021-04-28T00:30:32Z

lib/queue.rb

+    end
+
+    @store[@back] = element
+    @back = (@back + 1) % @size
  end

  def dequeue


CheezItMan · 2021-04-28T00:30:57Z

lib/queue.rb

  end

  def front
-    raise NotImplementedError, "Not yet implemented"
+    return @store[@front]
  end

  def size


Size should be the number of elements in the queue not the size of the underlying buffer.

CheezItMan · 2021-04-28T00:31:40Z

lib/queue.rb

  end

  def to_s
-    return @store.to_s
+    return @store[@front..(@back-1)].to_s


What if @back < @front

CheezItMan · 2021-04-28T00:31:49Z

lib/stack.rb

@@ -1,19 +1,19 @@
 class Stack


Beatress added 2 commits April 13, 2021 22:54

completed its stack

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finished assignment

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CheezItMan reviewed Apr 28, 2021

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Water - Beatrice #25

Water - Beatrice #25

Beatress commented Apr 24, 2021

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Water - Beatrice #25

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Water - Beatrice #25

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Beatress commented Apr 24, 2021

Stacks and Queues

Comprehension Questions

OPTIONAL JobSimulation

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