CS106A assignment3 --problem5 The Saint Petersburg Game

/* The Saint Petersburg Game  is a hypothetical casino game played by two players 
 * I begin by putting $1 on the table, and you then repeatedly flip a coin until it comes up tails. 
 * Each time the coin comes up heads, I double the amount of money on the table.
 * As soon as the coin comes up tails, the game is over and you win all the money.
 * program that plays the Saint Petersburg Game as many times as is necessary to earn a total of at least $20. 
 */
import acm.program.*;
import acm.util.RandomGenerator;

public class SaintPetersburgGame extends ConsoleProgram {
    /** The total number*/
    public static double total = 0;
    
    public void run() {
        
        //when total id less than 20,repeat the game; 
        while(total<=20){
            playGame();
        }
        
    }

    private void playGame() {
        //play a game until this turn comes up tail,then plus the number to total.
        Boolean comesUpHead = true;
        int num = 0;
        while(comesUpHead){
            RandomGenerator rgen = RandomGenerator.getInstance();
            comesUpHead = rgen.nextBoolean();
            num++;
        }
        println("This game, you earned $"+Math.pow(2, num)+".");
        total = total + Math.pow(2, num);
        println("Your total is $"+total+".");
    }
}