Question

Write a recursive method that counts the number of bowling pins given the number of pins in the back row: 1. public static int numPins (int num) numPins(0)-> 0 numPins(1) → 1 numPins(2)-> 3

Answer 1

Function:

public static int numPins(int num)

    {

        if(num == 0)

            return 0;

        // recursively find the number of pins in num - 1

        else

            return num + numPins(num - 1);

    }

Sample Program:

public class Bowling

{

    public static int numPins(int num)

    {

        if(num == 0)

            return 0;

        // recursively find the number of pins in num - 1

        else

            return num + numPins(num - 1);

    }

   

    public static void main(String[] args)

    {

        int i;

       

        for( i = 0 ; i <= 10 ; i++ )

            System.out.println("No of pins for num = " + i + " : " + numPins(i) + "\n");

    }

}

Sample Output:

C-Useruseresktopjavac Bowling-java C:NUsersNuser Desktop>java Bowling No of pins for num -0 0 No of pins for num1 1 No of pins for num -2 3 No of pins for num3 6 No of pins for num4 10 No of pins for num -5: 15 No of pins for num6 21 No of pins for num 28 No of pins for num 836 No of pins for num-945 No of pins for num1 55