Python期末考试题

Section 1

1.You are doing a survey and need to store the values of responses from your respondents. The

values are integers from 0 to 10, inclusive. What is the minimum number of bits you need to

store each value?

a. 3 bits

b.* 4 bits

c. 5 bits

d.10 bits

e.32 bits

2.The string “I love studying for final exams!” is stored in an array of characters called lies. What is

the value of lies[3]?

a.‘l’

b.* ‘o’

c.‘v’

d.‘e’

e.‘love’

3.Consider the following pseudo code. What condition needs to be added at *CODE HERE* for the

algorithm to correctly find the minimum in an array A?

Input:

A // array of integers

n // number of elements in array

Output:

Min // value of smallest element

Minimum(A, n) // name of algorithm

Min = A[0] // initialize min as first el.

for i = 1 to n-1

if *CODE HERE* then

Min = A[i]

endif

endfor

return Min

endMinimum

a.* A[i] < Min

b.A[i] > Min

c.A[i] >= Min

d.A[i] == Min

e.A[i] = Min

4.Suppose we have a list with variable name myList. The list contains [1, 2, 3, 4, 5]. What will the

list contain if we call myList.append(6) in Python?

a.[6, 1, 2, 3, 4, 5]

b.* [1, 2, 3, 4, 5, 6]

c.[1, 2, 3, 4, 5]

d.append is not a valid list method and cannot be used.

e.It will return a syntax error.

5.Recall Project 4 where you were asked to implement Convolve2D and Scale. Recall that

Convolve2D took a 3x3 kernel K and that Scale used a scale factor scf. If we were to use

Convolve2D in our implementation of Scale, what kernel would we use?

a.K = [ [ 0, 0, 0 ] , [ 0, 0, 0 ] , [ 0, 0, 0 ] ]

b.K = [ [scf, scf, scf ] , [scf, scf, scf ] , [scf, scf, scf ] ]

c.K = [ [scf/9, scf/9, scf/9 ] , [scf/9, scf/9, scf/9 ] , [scf/9, scf/9, scf/9 ] ]

d.* K = [ [ 0, 0, 0 ] , [ 0, scf, 0 ] , [ 0, 0, 0 ] ]

e.K = [ [scf, scf, scf ] , [scf, 0, scf ] , [scf, scf, scf ] ]

6.Consider the following recursive Python function. The function does not compute the factorial,

as intended. Which of the following statements are true?

# this function computes factorial

def Fact(n):

return n * Fact(n-1)

I. The function is missing a termination condition.

II. The function does not call itself recursively.

III. The function should return 1 if n==1.

IV. The return statement is not necessary.

V. The function will run for too long, making too many recursive calls.

a.I and II

b.I and III

c.I, II, and III

d.* I, III, and V

e.II and IV

Section 2

PART 1:

Q1. Which statements regarding recursion are true:

I.Recursion is implemented with a function calling itself with subset of original input as its input II.Recursion is implemented with a function calling itself with the original input as its input

III.Every recursive algorithm has an iterative solution

IV.Recursive algorithm must have a base case or terminating condition

a.I, II, III

b.I, II, III, IV

c.*I, III, IV

d.II, III

e.III, IV

Q2. Convert hexadecimal number “201” into decimal.

a.127

b.*513

c.401

d.101

Q3. What is the expression for the following expression tree:

a. ((5 + (z / -8)) * (4 ^ 2))

b. (((5 + z) / (-8 * 4)) ^ 2)

c. ((5 + ((z / -8) * 4)) ^ 2)

d. *(((5 + z) / -8) * (4 ^ 2))

PART 2:

Q1. Suppose you have a file named “test” containing the following 3 lines:

To whom it may concern:

I am not selling my textbooks.

Seriously.

What is the output of the following function:

def my_func():

file = open("test","rt")

contents = file.read()

print contents[11:12]

file.close()

a.* m

b. a

c.y

d.ma

e.ay

Section 3

1.

What is the result of the following Python code, given that parameters a and b are positive integers? def function(a,b):

for i in range(b):

a = a+1

return a

a. a+a

b. b-a

c. a-b

d. (*) a+b

2.

What is the result of the following Python code, given that parameters a and b are positive integers?

def function2(a,b):

result = 0

for i in range(b):

result = result + a

return result

a. a*a

b. (*) b*a

c. a-b

d. b/a

3.

What is the purpose of the following Python code, given that parameter a is a positive integer?

import math

def function3(a):

sqa = (int) (math.sqrt(a))

if sqa * sqa == a:

return True

return False

a. returns True if a is even

b. returns True if a is odd

c. *returns True if a is a perfect square

d. returns True if a is prime

6.

What is the purpose of the following Python code, given that input list is a list of integers?

def function6(list):

for i in range(len(list)-1):

if(abs(list[i]-list[i+1])>1):

return False

return True

a. returns True always

b. returns True if list size is even

c.returns True if numbers in list are in ascending order

d. * returns True if difference between neighboring numbers is no more than 1

1. How many different values can a one byte memory location have?

A. 2

B. 8 *

C. 256

D. 65,536

E. 4,294,967,300

2.Which of the following is the decimal value of the binary number 1110?

A. 10

B. 12

C. 13

D. 14

E. 15

3. What is the output produced by this code snipet below.

x = 3

if 2 > x :

print 'First'

else :

print 'Second'

if 2 > x :

print 'Third'

print 'Fourth'

print `Fifth'

A.* Second

Fourth

Fifth

B.Second

Third

Fifth

C.First

Second

Third

D.Fifth

E.First

Fifth

5. What is the output of func(5) for the following codes:

def func(n):

if n == 1:

return 1

if n == 2:

return 2

return func(n – 1) + func(n – 2)

a. 6

b.7

c.* 8

d.9

e.10

1) A number is represented in binary as 0100 1100. What is its equivalent hexadecimal representation?

a) *4C

b) 10F0

c) 410

d) 4D

2) Consider the following recursive algorithm to find the length (i.e. the number of nodes) in a linked list. Fill in the blank in the algorithm with the best option to find the length of the inked list correclty.

LinkedListLength(L)

if (L == Null)

return 0

else

return ________________

a) *1 + LinkedListLength(L.next)

b) LinkedListLength(L.next)

c) LinkedListLength(L)

3) A complete binary tree is one where all internal nodes have both the left and right children, i.e., neither link is null and all levels are filled. For a complete binary tree with 31 nodes, how many levels does the tree have?

a) *5

b) 4

c) 16

d) 15

4) What is the purpose of the *import* statement in Python?

a) * Allows the use of functions defined in other modules

b) Creates and names a new module.

c) Restricts the use of functions defined in the current module.

5) The following Python function prints out only the even numbers out of a given list.

import math

def func(list):

for x in list:

if(_______):

print x

Which of the following conditions can be used in the *if* statement?

a) x%2 == 0

b) x%2

c) x is even

d) x/2

6) What is the output of the following Python function? def func(str):

str = str.replace("apples", "oranges")

print(str)

str = "apples are not oranges"

func(str)

print(str)

a) *oranges are not oranges

apples are not oranges

b) apples are not oranges

oranges are not oranges

c) oranges are not oranges

oranges are not oranges

d) apples are not oranges

apples are not oranges

Section 6

Part 1

1. Order the following running times from fast to slow:

I. n II. log(n) III. nlog(n) IV. n2

a. I, II, III, IV

b. IV, I, II, III

c. *II, I, III, IV

d. II, III, I, IV

e. none of the above

2. What is the hexadecimal representation of the following binary number: 0101 1101 0001 0100

a. 6C18

*b. 5D14

c. 5E18

d. 6C14

e. none of the above

Part 2

1. Consider the following piece of python code:

def func(a):

b=eval(input('please type in a number:'))

c=a*b

return c

What is the output for the call func(5)and the user enters 2?

a. 2

b. 5

*c. 10

d. The program will produce an error

e. 52

2. Consider the following piece of python code:

def func(A):

sum = 0

for i in range(3):

sum = sum + A[i][2]

return sum

What is the return value of func([[1,2,3],[4,5,6],[7,8,9]])

a. 45

b. 19

*c. 18

d. 24

e. none of the above

3. Consider the following piece of python code:

count = 0

str = "No"

while str[0].lower() != 'Y'.lower():

print("The count is:",count)

count = count + 1

str = input("stop? Yes or No:")

print("while loop ended")

Which of the following input strings CANNOT end the while loop

a. “Yes!”

b. “Yeap!”

c. “yep”

d. * “End”

e. “Yuck”

Section 7

Part I

Question 1:

1.Sometime we are interested in swapping two variables without

using any temporary variable. The two variables a and b are

swapped as follows

a)a=a+b

b=a-b

a=a-b

b)a=a*b

b=a/b

a=a/b

c)Neither

d)*Both (a) and (b)

Question 2:

Consider a new type of tree in which each internal node has exactly four children. How many nodes at most are there on level 4, where level 0 corresponds to the root, level 1 corresponds to the children of the root, level 2 corresponds to the children of the children of the root, etc.?

a)16

b)64

c)*256

d)1024

e)None of the above

In computer science, binary numbers are used since computer hardware can easily represent 2 states. Assume that in 2050 a technological breakthrough will allow representing 3 states in hardware. What is the base 3 representation of the decimal number 12?

a)12

b)* 110

c)120

d)1100

e)None of the above

Part II

Question 1:

What is the output of the following python program?

def myFun(x, y, z):

if(z == 1):

return (x + y)

else:

return (y + x)

print(myFun(‘U’, myFun(‘V’, ‘Z’, 1), 0))

a)UVZ

b)UZV

c)VUZ

d)*VZU

e)None of the above

What is the output of the following python code? x = 10

def myFun(y):

x = y + 1

return x

myFun(x)

x = x+2

print(x)

a) 10

b) 11

c)* 12

d) 13

What is the output of the following python program?

def myFun(x):

x = x +1

return x

x = 10

x = x+1

myFun(x)

x = x+2

print(x)

a) 10

b) 11

c)*13

d) 14

Section 8

Correct answers are marked in red.

1.In order to use a function in your code from a different file, which line of code do you have to

have at the beginning of your file?

a.import filename

b.from filename import *

c.import from filename *

d.both a and b can be used

2.Which of the following recursive functions will accurately return the factorial of a number

passed as a parameter?

a.

def factorial(n)

if (n > 1)

return 1

else

return n * factorial(n-1)

b.

def factorial(n)

if (n <= 1)

return 1

else

return n * factorial(n-1)

c.

def factorial(n)

if (n <= 1)

return factorial(1)

else

return n * factorial(n-1)

d.

def factorial(n)

if (n <1)

return 0

else

return n * factorial(n-1)

3.What is the value of T[3][1] if T = [[24,1,2],[3,-1,3],[32,4,-1]]?

a. 4

b.32

c. 2

d.Index out of range

4.In order to take a string as user input for a program you can use the following line of code:

https://www.360docs.net/doc/036378098.html, = eval(input("What is your name?”))

https://www.360docs.net/doc/036378098.html, = input("What is your name?”)

https://www.360docs.net/doc/036378098.html, = eval("What is your name?”)

d.both a and b are ok to use

5.In order to append a node to a linked list in constant time you need:

a. A while loop

b. A for loop

c. A reference to the end of the list

d. A reference to the beginning of the list

6.If you convert 101 from binary to hexadecimal you get:

a. A

b. 4

c. 5

d. C

Section 9

The answer key is provided at the end of the section.

1. Which of the following statements is true?

A. A for loop can sometimes, but not every time, be replaced with a while loop.

B. A recursive algorithm can always be replaced with an iterative algorithm.

C. An iterative algorithm always works in linear time.

2. How many bits per symbol do you need to encode a set of 37 symbols?

A. 3

B. 4

C. 5

D. 6

3. What's wrong with the following recursive algorithm?

#This function is supposed to print the answer to the current problem

#and then print the answer to the next problem

def answerToExamQuestion(b):

printAnswerTo(b)

return answerToExamQuestion(b)

A. The word 'return' is not part of the Python language.

B. It will run forever and never finish the task.