Happy Number

Write an algorithm to determine if a number is "happy".

A happy number is a number defined by the following process: 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 (where it will stay), or it loops endlessly in a cycle which does not include 1. Those numbers for which this process ends in 1 are happy numbers.

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 + 0^2 = 1

 

public class Solution {
    public boolean isHappy(int n) {
        int newN = 0;
        HashSet<Integer> set = new HashSet<Integer>();
        
        while(!set.contains(n)){
            set.add(n);
            newN = 0;
            while(n != 0){
                newN += (n % 10) * (n % 10);
                n /= 10;
            }
            n = newN;
            
            if(n == 1) return true;
        }
        return false;
    }
}