S & Q

Question 1

Describe stacks

Answer 1

• Stacks are a linear “last in first out” data structure.
• The most recently added element is always the first element to leave the stack.
• Principal operations involve push to add elements and pop to remove.
• Essentially a data set as a stack of plates or books where you can only take the top element off the stack in order to remove things from it.

Question 2

List common uses for stacks

Answer 2

• Stacks are lists commonly used for storing undo\redo operations and processing languages.
• Internally, compilers evaluate expressions and syntax parsing implementing a stack.

Question 3

Describe queues

Answer 3

• Queues are a linear “first in first out” data structure.
• The first element to get in the queue will always be the first element to come out of the queue.
• Principal operations involve enqueue to add elements and dequeue to remove elements.
• A queue as a line at a grocery store where the person to reach the register first, gets helped first.

Question 4

List common uses for queues

Answer 4

• Queues are commonly used to maintain first-in-first-out order like HTTP requests to a web service or tasks on an operating system so the CPU can run one job at a time.

Question 5

Describe the general process of sorting a stack

Answer 5

• In order to sort a stack, all items most be popped off. Each item would be stored on a temporary list, then pushed back into the stack in a sorted order.