【leetcode】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

12 + 92 = 82

82 + 22 = 68

62 + 82 = 100

12 + 02 + 02 = 1

import java.util.HashSet;
import java.util.Set;

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