Stacks and Queues

Question 1

What is a queue?

Answer 1

A queue is a group of items all of the same type where items are added to the back of the queue and removed from the front.

Question 2

What is the principle of a Queue

Answer 2

FIFO

first-in first-out

Question 3

What are the methods of a Queue and what do they do?

Answer 3

add(x) = adds item x to the queue
remove() = removes and returns front item
peek() = returns the front item with no remove
size() = returns the # of the items in the queue
isEmpty() = checks to see if the queue is empty

Question 4

What are the methods of a Priority Queue and what do they do?

Answer 4

add(x) = adds item x to the pQueue
remove() = removes and returns min priority item 
peek() = returns the min item with no remove
size() = returns the # of items in the pQueue
isEmpty() = checks to see if the pQueue is empty

Question 5

What is the difference between the pQueue and queue?

Answer 5

pQueue orders them based on the ASCII table while queue does not order at all.

Question 6

What is a Stack

Answer 6

A stack is a group of items all of the same type where items are added to the top of the stack and removed from the top.

Question 7

What is the principle of Stacks?

Answer 7

LIFO

last-in first-out

Question 8

What are the methods of a Stack and what do they do?

Answer 8

push(x) = adds item x to the stack
add(x) = adds item x to the stack
pop() = removes and returns an item
peek() = returns the top item with no remove
size() = returns the # of items in the stack
isEmpty() = checks to see if the stack is empty

Question 9

What are the packages needed to call the data structures?

Answer 9

Queue = import java.util.Queue;

Stack = import java.util.Stack;

Both = import java.util.*;

Question 10

How does the principles work in data Structures.

Answer 10

As an example, the last-in first-in principle means that “the last element added is the first to be taken out”.