CMPUT 101 Practice MT2 Solutions

CMPUT 101 A2: Midterm 1 Name: Instructor: Marianne Morris Percentage: 15% ID: Date: Oct 14, 2021 This midterm exam has 3 questions. This is a closed book exam. No calculators or any other electronic devices allowed. Question 1 / 14 Question 2 / 12 Question 3 / 14 Total / 40

Question 1 : (14 marks) Boolean Logic: Prove the following DeMorgan’s law using the below truth table: (4 marks) NOT(A OR B) = NOT A AND NOT B A B NOT A NOT B A OR B NOT(A OR B) NOT A AND NOT B 0 0 1 1 0 1 1 0 1 1 0 1 0 0 1 0 0 1 1 0 0 1 1 0 0 1 0 0 Use the sum of products to derive the expression E from the following truth table: (4 marks) A B E 0 0 0 0 1 1 1 0 1 1 1 0 Evaluate the following expression when A = True and B = True: (2 marks) (A AND B) OR (NOT A AND NOT B) = (T and T) or (F and F) = T or F = True Evaluate the following statements, given the following list of strings, and write the correct Boolean value after evaluating each statement below: (4 marks) galaxy = ['sun', 'moon', 'star', 'planet', 'comet'] a) 'star' in galaxy or 'planet' not in galaxy = T or F = T b) 'moon' in galaxy and 'mars' not in galaxy = T and T = T c) 'planet' not in galaxy or 'sun' not in galaxy = F or F = F d) 'comet' in galaxy and 'earth' in galaxy = T and F = F E = (NOT A AND B) OR (A AND NOT B)

Question 3 : (14 marks) Trace through the following deciphering program and fill the table below then answer the questions that follow. (10 marks) mylist = [0, 3, 6, 8, 7] mystring = 'cklmnoptuwxyz' decipher = '' # empty string for i in range(len(mylist)): index = mylist[i] decipher = decipher + mystring[index] decipher = decipher + '#' print(decipher) i index mystring[index] decipher 0 0 ‘c’ ‘c’ 1 3 ‘m’ ‘cm’ 2 6 ‘p’ ‘cmp’ 3 8 ‘u’ ‘cmpu’ 4 7 ‘t’ ‘cmput’ What is the final decipher string that gets printed out? What condition decides the length, i.e., the size, of the decipher output string? (2 marks) ‘cmput#’ The size of the output string is determined by the size of my list. Explain how the program generates this decipher string and all the steps that it takes to generate the decipher string. (2 marks) 1) We initialize an empty string called decipher 2) We loop over the list mylist to obtain the value that represents an index in mystring 3) We obtain the character from mystring at the index obtained from mylist 4) We concatenate this character to the new decipher string every loop iteration