202. Happy Number

Leetcode: 202. 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:

Input: 19
Output: true
Explanation:
1^2 + 9^2 = 82
8^2 + 2^2 = 68
6^2 + 8^2 = 100
1^2 + 0^2 + 0^2 = 1

Solution:

class Solution {
    public boolean isHappy(int n) {
        if(n == 1) return true;
        int num = n, sum = 0;
        Set<Integer> checkLoopSet = new HashSet<>();
        while(num != 1 && num > 0){
            sum = 0;
            while(num > 0){
                sum += Math.pow((num % 10), 2);
                num /= 10;
            }
            if(checkLoopSet.contains(sum))
                return false;
            else
                checkLoopSet.add(sum);
            num = sum;
        }
        return true;
    }
}