Exam 3

Question 1

is one of the most commonly used data structures in computer science

Answer 1

A stack

Question 2

The stack’s storage policy is:

Answer 2

Last-In, First Out , or LIFO

Question 3

boolean empty()

Answer 3

Returns true if the stack is empty; otherwise, returns false.

Question 4

E peek()

Answer 4

Returns the object at the top of the stack without removing it.

Question 5

E pop()

Answer 5

Returns the object at the top of stack and removes it.

Question 6

E push (E obj)

Answer 6

Pushes an item onto the top of the stack and returns the item pushed.

Question 7

a string that reads identically in either direction , letter by letter (ignoring case )

Answer 7

Palindrome

Question 8

When analyzing arithmetic expressions, it is important to determine whether an expression is:

Answer 8

balanced with respect to parentheses

Question 9

The problem is further complicated if braces or brackets are used in ________ with _________.

The solution is to use:

Answer 9

conjunction

parentheses

Stacks

Question 10

PITFALL: attempting to pop an empty stack will throw an ______________ . You can guard against this by either:

Answer 10

EmptyStackexception

testing for an empty stack or catching the exception

Question 11

Stacks are so common in computing, that Java included a Stack class in its early versions :

Answer 11

import java.util.Stack;

Question 12

BUT, the Java Stack class extends Vector (a deprecated class which extends AbstractList) ... THEREFORE the class provides methods \_\_\_\_\_\_\_ to Stacks 
Its use is:

Answer 12

not traditional

no longer recommended

Question 13

like the stack, is a widely used data structure

Answer 13

The queue

Question 14

A queue differs from a stack in one important way:

Answer 14

stack is a LIFO list Last-In, First-Out

while a queue a is FIFO list - First-In, First -Out

Question 15

Operating systems use queues to:

Answer 15

Keep track of tasks waiting for a scarce resource

ensure that the tasks are carried out in FIFO order

Question 16

Printing queue:

Answer 16

Printing is so much slower than the process of selecting pages to print, so a queue is used

Question 17

remove() and poll() differ only on what happens when the queue is empty.

Answer 17

remove() removes the entry at the front and return NoSuchElementException

poll() removes the entry at the front and returns null

We use remove()

Question 18

peek() and element() differ only on what happens when the queue is empty.

Answer 18

peek() returns entry at the front and returns null

element() returns the entry at the front and returns NoSuchElementException

We use peek()

Question 19

The __________ class provides methods for inserting and removing elements at either end of a linked list, which means all _______ methods can be implemented easily

Answer 19

LinkedList

Queue

Question 20

The Java ________ class implements the _____ interface

Answer 20

Linkedlist

Queue