/**
* Write a Java program to find and print the Happy numbers between m and n.
Happy number: Starting with any positive integer, replace the number by the sum of the squares of its digits,
and repeat the process until the number equals 1, or it loops endlessly in a cycle which does not include 1.
Example: 19 is a happy number
1^2 + 9^2=82
8^2 + 2^2=68
6^2 + 8^2=100
1^2 + 0^2 + 02=1
The first few happy numbers are 1, 7, 10, 13, 19, 23, 28, 31, 32, 44, 49, 68, 70, 79, 82, 86, 91, 94, 97, 100, ...
*/
import java.util.*;
public class HappyNum
{
public static int digitSq(int x) // recursive function to find square of digits of the number
{
if(x<10)
return x*x;
else
return (x%10)*(x%10) + digitSq(x/10);
} // end of digitSq()
public static boolean isHappy(int num, int i) // recursive function to check whether the no. is happy or not
{
//System.out.println(num);
if(num==1)
return true;
else if(i==15)
return false;
else
return isHappy( digitSq(num), i+1);
} // end of isHappy()
public static void main()
{
Scanner sc=new Scanner(System.in);
System.out.print("\nEnter lower limit : ");
int m=sc.nextInt();
System.out.print("\nEnter upper limit : ");
int n=sc.nextInt();
System.out.println("The Happy numbers are : ");
for(int i=m;i<=n;i++)
{
if( isHappy(i, 0) )
{
System.out.print(i+" ");
}
}
} // end of main()
} // end of class
Q.9 WAP in C/ C++/ java to check whether the number is a Special Number or not. Definition: If the sum of the factorial of digits of a number (N) is equal to the number itself, the number (N) is called a special number. INPUT : 145 The digits of the number are: 1, 4, 5 Factorial of digits: 1! = 1 4! = 4*3*2*1 = 24 5! = 5*4*3*2*1 = 120 Sum of factorial of digits = 1 + 24 + 120 = 145 Hence, the given number 145 is a special number. Solution : #include <stdio.h> int factorial ( int x) // function to return factorial of the number { int f = 1 ; for ( int i = 1 ; i <= x; i ++ ) { ...
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