Spring Semester 09 Exam #1 Dr. Dillon. (02/19)

Transcription

1 Spring Semester 09 Exam #1 Dr. Dillon. (02/19) Form 1 A Last name (printed): First name (printed): Directions: a) DO NOT OPEN YOUR EXAM BOOKLET UNTIL YOU HAVE BEEN TOLD TO BEGIN. b) You have 90 minutes to complete the exam (12:40 2:00 pm) c) This exam booklet contains 26 multiple choice questions, each weighted equally (5 points) and one 20 point programming problem. (27 questions, 10 total pages) d) There is an ASCII table on the last page of the exam for your reference. e) You may also use one 8.5" x 11" note sheet during the exam. No other reference materials or calculating devices may be used during the examination. f) Questions will not be interpreted during the examination. g) You should choose the single best alternative for each question, even if you believe that a question has multiple correct answers, is ambiguous or contains a typographic error. h) Fill in the requested information at the top of this exam booklet. i) Use a #2 pencil to encode information on the OMR form. j) Encode the following on the OMR form: Last name and first initial MSU PID Exam form (see the top right corner of this page) k) Sign the OMR form. l) Only answers recorded on your OMR form will be counted for credit for multiplechoice questions. m) Completely erase any responses on the OMR form that you wish to delete. n) You must turn in this exam booklet and the OMR form when you have completed the exam. When leaving, please be courteous to those still taking the exam. Good luck. Timing tip. A rate of 2.5 minutes per multiple choice problem leaves 15 minutes to write the program (worth 20 points) at the end :a, 02:c, 03:c, 04:d, 05:b, 06:a, 07:c, 08:d, 09:d, 10:d, 11:e, 12:a, 13:a, 14:b, 15:c, 16:b, 17:d, 18:a, 19:c, 20:b, 21:a, 22:a, 23:b, 24:a, 25:b, 26:a

2 Figure 1 1) In Figure 1, if the user enters 6 at the prompt, what is printed by Line E? a) s = 6.0 b) s = 12.0 c) s = 6 d) s = 12. 2) In Figure 1, if the user enters 6 at the prompt, what is printed by Line F? a) t = 0 b) t = 1 c) t = 2 d) t = 3. 3) In Figure 1, if the user enters 6 at the prompt, what is printed by Line G? a) num = 0 b) num = 0.0 c) num = 2 d) num = 2. 4) In Figure 1, what effect would removing Line A have, assuming the user enters 6? a) No affect the program would produce the same results as before. b) The while loop would not terminate. c) An error would occur when the condition (num > 0) is evaluated in Line B. d) An error would occur when the condition num%5 is evaluated in Line C.. 5) In Figure 1, what effect would removing Line D have, assuming the user enters 6? a) No affect the program would produce the same results as before. b) The while loop would not terminate. c) The program could not be run because of a syntax error. d) The program would print a larger value for num at Line G.

3 6) In Figure 1, type does the variable num have when Line D is executed? a) Integer (int) b) Boolean c) String (str) d) Its type depends on which suite of the if instruction, which begins at Line C, is executed.. 7) Which of the following has the effect of swapping (interchanging) the values of the variables a and b? a) a = b b) t, a, b = a, b, t c) a, b = b, a d) a.swap(b) 8) Which of the following statements is true? a) A modern day computer system often has more than one processor. b) An external hard drive is an example of secondary storage. c) Primary storage requires power to retain information. d) All of the above.. 9) Suppose you type the following into the Python shell at the >>>-prompt: range(12,100,10)[-1] What value does the shell return? a) A side-effect occurs, but no value is returned. b) 100 c) 99 d) 92.

4 Figure 2 10) In Figure 2, if the user types wo at the prompt what value is output by Line E? a) wooo b) wooooo c) woooowoooo d) wooooowooooo. 11) In Figure 2, if the user types hi at the prompt what value is output by Line E? a) hihihihi b) hihi c) hioohioo d) hioo 12) In Figure 2, if the user types 5a 3b at the prompt what value is output by Line E? a) 5a 3b5a 3b b) 5a5a5a c) 5aoooo d) 5aoooo5aoooo. 13) Which statement about the instruction in Line C of Figure 2 is true? a) It produces a side effect. b) It evaluates the expression ( oo ) on the right hand side of the equals sign (=) to obtain a value, and associates this value to the name mystr. c) It prints the value of the expression mystr + oo d) Depending on the type, any one of the above could be true. is true. 14) Which statement about the instruction in Line D of Figure 2 is true? a) Depending on the user input, it may be executed multiple times. b) Depending on the user input, it may never be executed. c) It is always executed exactly once, regardless of the user input. d) It is always executed multiple times, regardless of the user input..

5 Figure 3 15) Which of the following Python programs implement the control flow graph shown in Figure 3? a) while True: n = int(raw_input( Enter an int: )) if n== A1: continue elif n == A2: break print what print ever b) while True: n = int(raw_input( Enter an int: )) if n== A1: continue elif n == A2: break print what print ever c) while True: n = int(raw_input( Enter an int: )) if n== A1: continue elif n == A2: break print what print ever d) All of the (a) -- (c) e) None of (a) -- (c)

6 Figure 4 16) In Figure 4 what is printed by Line E? a) len(mylist) is 3 b) len(mylist) is 4 c) len(mylist) is 6 d) len(mylist) is 8 17) In Figure 4 what is printed by Line F? a) len(yrlist) is 3 b) len(yrlist) is 4 c) len(yrlist) is 6 d) len(yrlist) is 8 18) In Figure 4, what is printed by Line G? a) len(thlist) is 3 b) len(thlist) is 4 c) len(thlist) is 6 d) len(thlist) is 8 19) In Figure 4, what is printed by Line H? a) 1 b) 2 c) [1, 2] c) [2] 20) In Figure 4, what output is produced by execution of Line I? a) [1, 2] b) [1, 3] c) [2, 3] d) [2, 4] 21) Which of the following is true? a) In Python, a string value cannot be modified. b) In Python, the type of a variable is determined by its name. c) In Python, all data structures are mutable. d) All of the above..

7 22) What is printed by the following Python instruction if the value of val is 1: if val%2: print 0 print 1 a) 0 b) 1 c) Nothing the instruction contains a syntax error and cannot be executed. d) Nothing an error occurs when the instruction is executed. 23) What is printed by the following Python instruction if the value of val is 1: if 0 < val/3: print 0 print 1 a) 0 b) 1 c) Nothing the instruction contains a syntax error and cannot be executed. d) Nothing an error occurs when the instruction is executed. 24) What is printed by the following Python instruction if the value of val is 1: if 0 < (val/3.0) < val: print 0 print 1 a) 0 b) 1 c) Nothing the instruction contains a syntax error and cannot be executed. d) Nothing an error occurs when the instruction is executed. 25) What is printed by the following Python instruction if the value of val is 1: print (0!= val) or val a) 1 b) True c) (0!= val) or val d) Nothing an error occurs when the instruction is executed 26) What is printed by the following Python instruction if the value of val is 1: print val or (0!= val) a) 1 b) True c) val or (0!= val) d) Nothing an error occurs when the instruction is executed

8 27. Program question 20pts. Please, write on scrap paper first, then copy your answer to the next page. Make sure you put your name on the solution and hand it in at the end of the test. Background Every integer greater than 1 has a unique prime factorization into a product of one or more prime numbers in ascending order. For example: 12 = 2 * 2 * 3 39 = 3 * = 151 Requirements Your program must prompt for an integer greater than 1, and print out the integer together with its prime factorization. Hints You can find the prime factors of a number n by a very simple algorithm: Find the smallest integer n 1 larger than 1 that divides n and calculate the quotient q 1 of the n divided by n 1. If q 1 is greater than 1, then find the smallest integer n 2 larger than 1 that divides q 1 and calculate the quotient q 2 of q 1 divided by n 2. If q 2 is greater than 1, continue in this fashion to find n 3 and q 3. Keep going until you get a quotient of 1. The factors of n then consist of the divisors that you found: n 1, n 2, n 3, For example: Suppose the starting number is 126 o 2 is the smallest number larger than 1 that divides 126; the quotient is 63 o 3 is the smallest number larger than 1 that divides 63; the quotient is 21 o 3 is the smallest number larger than 1 that divides 21; the quotient is 7 o 7 is the smallest number larger than 1 that divides 7; the quotient is 1 Thus, the divisors are 2, 3, 3, 7. That is, 126 = 2 * 3 * 3 * 7 Start with a properly initialized list and add onto it until you have accumulated all the prime factors. Then print out the original number and the list of factors in ascending order. To save time, you do not have to worry about formatting the output as above. For example, for 126, you can simply output the message: The list of prime factors of 126 is: [2,3,3,7] Your program does not need to do any error checking. If the user gives it erroneous input, it can crash. Your program does not need to be efficient or elegant. But it must work as described for full credit. Be clear about your indentation! Write legibly!!

9 CSE 231, Spring 09, Dr. Dillon, Exam 1 written solution Name: Section:

10 ASCII Table