Page 403 - computer science (868) class 11
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int countdigit(int a) : Counts and returns the number of digits in ‘a’ using the recursive technique
th
int sumpower(int a, int p) : Using recursive technique, returns sum of p power of the digits of the number stored
in variable a
void isArmstrong() : Calls countdigit(int) and sumpower(int, int) and prints if the number is an Armstrong
number or not
Specify the class Armstrong giving details of the methods void getnum(), int countdigit(int) and int sumpower(int,int) and void
isArmstrong(). Also define the main() function to create an object and call the functions accordingly to enable the task.
2. The Evil number is a special positive whole number that has an even number of 1’s in its binary equivalent.
6 is an evil number as its binary equivalent 110 has 2 1’s.
9 is an evil number as its binary value 1001 has 2 1’s.
15 is an evil number as its binary value 1111 has 4 1’s.
A class called Evilnum is defined to check if a number is an evil number or not. Some of the members of the class are given below:
Class name : Evilnum
Data Members/Instance variables
num : To store the number
Member Methods/Member functions
void getnum() : Accepts number in num from the user
String tobinary(int a) : Returns the binary equivalent of number ‘a’ as String using the recursive technique
int countones(String s) : Using recursive technique, returns the frequency of ‘1’ in its binary form ‘s’ expressed
as String
void isEvil() : Calls tobinary(int) and countones(String) and prints if the number is an evil number or not
Specify the class Evilnum giving details of the methods void getnum(), String tobinary(int) and int countones(String) and void
isEvil(). Also define the main() method to create an object and call the methods accordingly to enable the task.
3. A number is said to be Krishnamurthy if the sum of factorial of its digits is equal to that number. For example, number = 145
= 1! + 4! + 5! = 1 + 24 + 120 = 145
A class called Kmurthy is defined to check if a given number is Krishnamurthy number or not. The detail of the class is given below:
Class name : Kmurthy
Data Members/instance variables
num : To store the number
Member Methods/Member functions
void getnum() : Accepts number in num from the user
int factorial(int a) : Returns the factorial of a using recursive technique
int sumfact(int x) : Calls method int factorial(int) and using recursive technique calculates and
returns the sum of factorial of the digits of number ‘X’
void check() : Calls int sumfact(int x) and checks if the given number is a Krishnamurthy number
or not
Specify the class Kmurthy giving details of the methods void getnum(), int factorial(int) and int sumfact(int) and void check(). Also,
define the main() function to create an object and call the functions accordingly to enable the task.
4. Monodigit numbers are the numbers consisting of a single repeating digit, e.g., 77, 999, 8888, etc.
A class called Mono is defined to check if a given number is monodigit number or not. The detail of the class is given below:
Class name : Mono
Data Members/Instance variables
num : To store the number
Member Methods/Member functions
void getnum() : Accepts number in num from the user
boolean check(int n, int d) : Using recursive technique, checks if the number ‘n’ whose last digit is ‘d’ is a
mono digit number or not and returns true or false accordingly
void print() : Calls boolean check(int,int) and prints appropriate message
Specify the class Mono giving details of the methods void getnum(), boolean check(int, int) and void print(). Also, define the
main() function to create an object and call the functions accordingly to enable the task.
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Recursion 401

