# rball.py # Simulation of a racquetball game. Illustrates use of random # numbers and functions to implement top-down design. from random import random def main(): printIntro() probA, probB, n = getInputs() winsA, winsB = simNGames(n, probA, probB) printSummary(winsA, winsB) def printIntro(): # Prints an introduction to the program print "This program simulates a game of racquetball between two" print 'players called "A" and "B". The abilities of each player is' print "indicated by a probability (a number between 0 and 1) that" print "the player wins the point when serving. Player A always" print "has the first serve.\n" def getInputs(): # Returns probA, probB, number of games to simulate a = input("What is the prob. player A wins a serve? ") b = input("What is the prob. player B wins a serve? ") n = input("How many games to simulate? ") return a, b, n def simNGames(n, probA, probB): # Simulates n games of racquetball between players whose # abilities are represented by the probability of winning a serve. # Returns number of wins for A and B winsA = winsB = 0 for i in range(n): scoreA, scoreB = simOneGame(probA, probB) if scoreA > scoreB: winsA = winsA + 1 else: winsB = winsB + 1 return winsA, winsB def simOneGame(probA, probB): # Simulates a single game of racquetball between two players whose # abilities are represented by the probability of winning a serve. # Returns final scores for A and B serving = "A" scoreA = 0 scoreB = 0 while not gameOver(scoreA, scoreB): if serving == "A": if random() < probA: scoreA = scoreA + 1 else: serving = "B" else: if random() < probB: scoreB = scoreB + 1 else: serving = "A" return scoreA, scoreB def gameOver(a,b): # a and b are scores for players in a racquetball game # Returns true if game is over, false otherwise return a == 15 or b == 15 def printSummary(winsA, winsB): # Prints a summary of wins for each player. n = winsA + winsB print "\nGames simulated:", n print "Wins for A: %d (%0.1f%%)" % (winsA, float(winsA)/n*100) print "Wins for B: %d (%0.1f%%)" % (winsB, float(winsB)/n*100) if __name__ == "__main__": main()