This is the base questions: Modify Listing 5.4, page 139, so it meets the following requirements:

Like Listing 5.4, the new program shall present random subtraction questions to the player until the player either (i) misses three questions in a row, or (iii) enters -1 to quit the game. Notice there is no maximum number of questions

The program shall keep track of the number of questions presented to the player, and the number of questions that were answered correctly.

At the end of the game the program shall:

Report the number of correct answers and the score. The score will be determined using the following expression: score = (questions answered correctly / total questions tried) * 100 Notice that if the user did not answer any questions, the score is zero.

Report whether the current score is the new highest score.

Ask the player whether s/he wants to play again. If the answer is N, the game ends. If the answer is Y, the game restarts.

This is the base program:

import random import time

correctcount = 0 #number of correct answers count = 0 #count the number of questions number_of_questions = float('inf') #constant starttime = time.time() #get start time end = eval(input("Enter -1 to stop or 0 to continue:"))

while count < number_of_questions: number1 = random.randint(0,9) number2 = random.randint(0,9) if number1 < number2: number1, number2 = number2, number1 answer = eval(input("what is" + str(number1) + "-" + str(number2) + "?")) if number1 - number2 == answer: print("You are correct!") correctcount += 1

else: print("Your answer is wrong. ", number1, "-", number2, "is", number1 - number2) count += 1

endtime = time.time() testtime = int(endtime - starttime) print("Your score is", (correctcount/number_of_questions)*100) #counts the amount of correct answers and divides by the number of questions then multiplies by 100 to get score for the game. print("Correct count is", correctcount, "out of", number_of_questions, " test time is", testtime, "seconds")