Question 1

If the current state of the stack is [ x, y, z ] where x is the bottom of the stack and z is the top of the stack, what is the state of the stack and the value returned after a pop operation?

Accepted Answer

A)   the state is [ x, y ]; z is returned
B)   the state is [ x, y, z ]; z is returned
C)   the state is [ y, z ]; x is returned
D)   the state is [ x, y, z ]; x is returnedE) A) and D)
F) None of the above

Question 2

Access to a stack is restricted to the bottom end.

Accepted Answer

A) True 
 B)False

Question 3

The equation 17 46 + is an example of postfix form.

Accepted Answer

A) True 
 B)False  True

Question 4

When using a stack to evaluate the balance of brackets and parentheses in an expression, what is the first step?

Accepted Answer

A)   push opening brackets onto the stack while scanning the expression
B)   pop closing brackets onto the stack while scanning the expression
C)   push closing brackets onto the stack while scanning the expression
D)   pop opening brackets onto the stack while scanning the expressionE) A) and D)
F) B) and C)

Question 5

If the entire postfix expression is 9 1 4 + - 2 *, what is the final value?

Accepted Answer

A)   12
B)   8
C)   17
D)   10E) A) and B)
F) A) and C)

Question 6

The push operation for a stack raises an error if the stack is empty.

Accepted Answer

A) True 
 B)False

Question 7

With a stack, you always access the item that has been most recently added.

Accepted Answer

A) True 
 B)False

Question 8

The operator in an infix expression follows the operands.

Accepted Answer

A) True 
 B)False

Question 9

Which of the following begins in a predefined starting state and then moves from state to state in search of a desired ending state?

Accepted Answer

A)   backtracking algorithm
B)   memory management algorithm
C)   infix to postfix converter
D)   postfix to infix converterE) B) and D)
F) None of the above

Question 10

In the linked implementation of a stack, what type of helper function simplifies the __iter__ method?

Accepted Answer

A)   binary
B)   sequential
C)   recursive
D)   randomE) None of the above
F) B) and C)

Question 11

What is the resulting postfix expression from the following infix expression? (12 + 5)  * 2 - 3

Accepted Answer

A)   12 5 2 + * 3 -
B)   12 5 + 2 3 * -
C)   12 5 + 2 * 3 -
D)   12 5 2 + 3 - *E) All of the above
F) None of the above

Question 12

What is the function of the PVM?

Accepted Answer

A)   converts methods to subroutines
B)   executes a python program from bytecodes
C)   compiles Python code into assembly language
D)   links a Python program to imported modulesE) A) and D)
F) A) and C)

Question 13

Stacks adhere to a LIFO protocol.

Accepted Answer

A) True 
 B)False

Question 14

In what way doesn't the Python list data structure accurately emulate a stack?

Accepted Answer

A)   the append method pushes elements onto the stack
B)   the pop method removes and returns the top element
C)   a list uses an array as the underlying data structure
D)   list methods allow manipulation of items at any positionE) B) and C)
F) A) and D)

Question 15

A stack structure is a built-in part of the Python language.

Accepted Answer

A) True 
 B)False  False

Question 16

What is the resulting infix expression from the following postfix expression? 17 4 - 6 + 8 *

Accepted Answer

A)   17 - (4 + 6 * 8) 
B)   17 - (4 + 6)  * 8
C)   (17 - 4)  + (6 * 8) 
D)   (17 - 4 + 6)  * 8E) A) and B)
F) None of the above

Question 17

A token in the postfix expression evaluation algorithm is an operand or operator.

Accepted Answer

A) True 
 B)False

Question 18

Which of the following is true about a postfix expression?

Accepted Answer

A)   the operator is between its two operands
B)   the operator follows its two operands
C)   stack of bricks
D)   table of contentsE) All of the above
F) B) and C)

Question 19

In the following code that defines the push method for the array-based stack, what is the missing code? def push (self, item) :

Self.size += 1

Accepted Answer

A)   self.items += 1
B)   self.items[ len(self)  ] = item
C)   items[ size ] = len(self.item) 
D)   item = self.items[ self.size + 1 ]E) A) and C)
F) A) and D) B

Question 20

Which of the following is NOT an example of a stack in everyday life?

Accepted Answer

A)   a spindle of blank DVDs
B)   a stack of plates in a cafeteria line
C)   a pile of napkins
D)   a jar of jellybeansE) A) and D)
F) C) and D)

Exam 7: Stacks

If the current state of the stack is [ x, y, z ] where x is the bottom of the stack and z is the top of the stack, what is the state of the stack and the value returned after a pop operation?

Correct AnswerverifiedShow Answer

Access to a stack is restricted to the bottom end.

Correct AnswerverifiedShow Answer

The equation 17 46 + is an example of postfix form.

Correct AnswerverifiedTrue

When using a stack to evaluate the balance of brackets and parentheses in an expression, what is the first step?

Correct AnswerverifiedShow Answer

If the entire postfix expression is 9 1 4 + - 2 *, what is the final value?

Correct AnswerverifiedShow Answer

The push operation for a stack raises an error if the stack is empty.

Correct AnswerverifiedShow Answer

With a stack, you always access the item that has been most recently added.

Correct AnswerverifiedShow Answer

The operator in an infix expression follows the operands.

Correct AnswerverifiedShow Answer

Which of the following begins in a predefined starting state and then moves from state to state in search of a desired ending state?

Correct AnswerverifiedShow Answer

In the linked implementation of a stack, what type of helper function simplifies the __iter__ method?

Correct AnswerverifiedShow Answer

What is the resulting postfix expression from the following infix expression? (12 + 5) * 2 - 3

Correct AnswerverifiedShow Answer

What is the function of the PVM?

Correct AnswerverifiedShow Answer

Stacks adhere to a LIFO protocol.

Correct AnswerverifiedShow Answer

In what way doesn't the Python list data structure accurately emulate a stack?

Correct AnswerverifiedShow Answer

A stack structure is a built-in part of the Python language.

Correct AnswerverifiedFalse

What is the resulting infix expression from the following postfix expression? 17 4 - 6 + 8 *

Correct AnswerverifiedShow Answer

A token in the postfix expression evaluation algorithm is an operand or operator.

Correct AnswerverifiedShow Answer

Which of the following is true about a postfix expression?

Correct AnswerverifiedShow Answer

In the following code that defines the push method for the array-based stack, what is the missing code? def push (self, item) : < missing code > Self.size += 1

Correct AnswerverifiedB

Which of the following is NOT an example of a stack in everyday life?

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
True

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

In the linked implementation of a stack, what type of helper function simplifies the iter method?

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
False

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
B

Correct Answer
verified