Question

write a program in Java
to input number user ( by BufferedReader ) and print whether they are Happy number or not.
​

Answer 1

Answer:

import java.io.*;

import java.io.BufferedReader;  

import java.io.IOException;  

import java.io.InputStreamReader;  

class Main {  

// Utility method to return sum of square of  

// digit of n  

static int numSquareSum(int n)  

{  

int squareSum = 0;  

while (n!= 0)  

{  

 squareSum += (n % 10) * (n % 10);  

 n /= 10;  

}  

return squareSum;  

}  

// method return true if n is Happy number  

static boolean isHappynumber(int n)  

{  

int slow, fast;  

// initialize slow and fast by n  

slow = fast = n;  

do

{  

 // move slow number  

 // by one iteration  

 slow = numSquareSum(slow);  

 // move fast number  

 // by two iteration  

 fast = numSquareSum(numSquareSum(fast));  

}  

while (slow != fast);  

// if both number meet at 1,  

// then return true  

return (slow == 1);  

}  

// Driver code to test above methods  

public static void main(String[] args)  

{  

BufferedReader inp = new BufferedReader (new InputStreamReader(System.in));

 String str=inp.readLine();

int n= Integer.parseInt(str);

if (isHappynumber(n))  

 System.out.println(n +  

 " is a Happy number");  

else

 System.out.println(n +  

 " is not a Happy number");  

}  

}

Explanation:

Please Mark me as Brainiest...

Example

13=$1^{2}$ + $3^{2}$ =10

10=$1^{2}$ + $0^{2}$ =1

Like this processing ends with one then it is happy number otherwise not.