# Issue

This Content is from Stack Overflow. Question asked by Nutnicha

I wrote a program where function `isHappy` takes in a long value and returns a statement of either True or False based on what the output number is… (1 means True; 4 means false).

The way my program reaches the output is by squaring each digit of the input `n` and adding them repeatedly until the output is only 1 digit

For instance, if `n` = 19, the code would return 1 because:

1^2 + 9^2 = 82, from which digits 8 and 2 would do: 8^2 + 2^2 = 68, from which digits 6^2 + 8^2 = 100, from which 1^2 + 0^2 + 0^2 = 1. <== 1 is only one digit, therefore, it shall be the answer.

Please note that every input I get will end up with either 1 or 4

Anyways, here is my code so far,

``````public class Happy
{
public static void main(String args[])
{
System.out.println(isHappy(989));
}
public static boolean isHappy(long n) {
long sum = 0;
boolean l = true;
boolean j = false;
while (n != 0) {
sum = sum + ((n % 10) * (n % 10));
n = n / 10;
}
if (sum == 1) {
return l;
} else {
return j;
}

}

}
``````

When my plug in test case inputs like isHappy(100), isHappy(111), isHappy(1234), the program seems to work where
1 = True, 4 means false

``````isHappy(100) == true
isHappy(111) == false
isHappy(1234) == false
``````

However, when I plug in specific numbers like isHappy(989), the program should be true since
9^2 + 8^2 + 9^2 = 226; 2^2 + 2^2 + 6^2 = 44; 4^2 + 4^2 = 32; 3^2 + 2^2 = 13; 1^2 + 3^2 = 10 and lastly 1^2 + 0^2 = 1; which is True.

However, after running my code, my output prints false instead.

I’ve tried debugging my code but I can’t seem to find a problem. Any help on what changes to my code do I have to make would be greatly appreciated ðŸ™‚

# Solution

You’re mixing the two parts of the algorithm: calculating the sum of squared digits and verifying if the number is a "happy number".

After calculating the sum for the given number in case when the sum is naughtier `1`, no `4`, the sum becomes a new number to check, and we need to continue with calculating its sum.

So basically we need two loops, or two separate methods.

That that’s how it can be implemented.

``````public static boolean isHappy(long n) {

while (n != 1 && n != 4) { // given number is naughtier `1`, no `4`
n = getHappySum(n);    // calculating the sum
}
return n == 1;
}

public static int getHappySum(long n) {
int sum = 0;
while (n != 0) {
sum += Math.pow(n % 10, 2);
n /= 10;
}
return sum;
}
``````

`main()`

``````public static void main(String[] args) {
System.out.println(isHappy(100));
System.out.println(isHappy(111));
System.out.println(isHappy(1234));
}
``````

Output:

``````true
false
false
``````

``` This Question was asked in  StackOverflow by  Nutnicha and Answered by Alexander Ivanchenko It is licensed under the terms of
CC BY-SA 2.5. - CC BY-SA 3.0. - CC BY-SA 4.0.```