Question

Problem Description: Game: Bean Machine or Galton Box

To figure out if the ball falls to Left or Right, you can generate a random number using Math.random(). If this random number is greater than or equal to 0.5 we assume the ball falls to the Right otherwise it falls to the Left (or vise versa).

If there are 8 slots, the ball should hit 7 nails (8 -1), thus you should run a loop 7 times to figure out the path for that ball. If you have N balls, this whole process should be repeated N times. Here is a basic algorithm.

# of balls = N

# of slots = K

array of K elements

for ( i = 0 to N) {

   int R = 0;

   for (j = 0 to K-1) {

        if ( random number >= 0.5)

                  R++;

}//end loop j

array[R] ++;

}// end loop i

Output the array to show how many balls are in each slot.

Things to DO!!!!!

Analysis: (3 points)

(Describe the problem including inputs and outputs in your own words.)

Design: (3 points)

(Describe the major steps in your algorithm for solving the problem.)

Coding: Write a well documented and properly indented Java source program. Your program should have a block comment with your name and a statement of purpose at the very top. Use meaningful variable names. You must have proper labels and informative statements for all inputs and outputs. (10 points)

Testing: (Describe how you test this program, you should use your own input data to test not just the test cases given in sample runs.) (4 points)

Test your program according to following test schedule and generate output to show the number of balls in each slot.

N	K
10	8
50	10
100	20
500	30

What to Submit:

1. A PDF with descriptions of Analysis, Design, and Testing. Must have a title with your name and assignment number. (Do not submit a Word document!!!!)
2. Error free Java source program (Programs with syntax errors receive 0 credit) with methods, proper comments and indentation. Java source program is the program you wrote with .java file extension. (Do not submit a Word or any other document of your code!!!!)
3. The Program outputs for the 4 different test cases in a PDF

Answer 1

Program:=

import java.util.*;
public class gbox
{
    public static void main(String[] args)
    {
     Scanner input = new Scanner(System.in);

      // user to enter the number of the balls
        System.out.print("Enter the number of balls to drop: ");
        int numberOfBalls = input.nextInt();
        String[] ballPaths = new String[numberOfBalls];

        // user to enter the number of slots
        System.out.print("Enter the number of slots in the bean machine: ");
        int numberOfSlots = input.nextInt();
        int[] slots = new int[numberOfSlots];

        // display ball paths
        for (int i = 0; i < numberOfBalls; i++) {
            ballPaths[i] = dropBall(slots);
            System.out.printf("%10s\n", ballPaths[i]);
        }
        System.out.println("");
        printArray(slots, numberOfBalls);
    }

   //dropBall method returns the string L or R randomly
    public static String dropBall(int[] slot)
   {
          StringBuilder ballPath = new StringBuilder();
           for (int i = 0; i < slot.length - 1; i++)
          {
            int random = (int)(Math.random() * 10) % 2;
            if (random >=0.5)
                ballPath.append("R");
            else
                ballPath.append("L");
           }
          int position = getBallPosition(ballPath.toString(), 'R');
          slot[position]++;
          return ballPath.toString();
    }

    public static int getBallPosition(String str, char a)
   {
        int count = 0;
        for (int i = 0; i < str.length(); i++)
       {
            if (str.charAt(i) == a) count++;
        }
        return count;
    }

    public static void printArray(int[] slots, int numberOfBalls)
     {
            while (!isEmpty(slots))
           {
                if (isRowEmpty(slots, numberOfBalls))
               {
                    numberOfBalls--;
                    continue;
                }
                for (int i = 0; i < slots.length; i++)
               {
                    if (slots[i] >= numberOfBalls)
                   {
                        System.out.printf("%2c", 'O');
                        slots[i]--;
                    }
                    else System.out.printf("%2c", ' ');
                }
                numberOfBalls--;
                System.out.println("");

            }
    }

    public static boolean isEmpty(int[] slots)
   {
        for (int slot : slots)
       {
            if (slot != 0)
            {
                return false;
            }
        }
        return true;
    }

    public static boolean isRowEmpty(int[] slots, int rowNum)
    {
        for (int slot : slots)
        {
            if (slot == rowNum)
           {
                return false;
            }
        }
        return true;
    }
}

Output: