Happy Number leetcode

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

• 12 + 92 = 82
• 82 + 22 = 68
• 62 + 82 = 100
• 12 + 02 + 02 = 1

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