From LeetCode 202. Happy Number

### Description

Write an algorithm to determine if a number `n`

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.
- 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.

Return `true`

*if* `n`

*is a happy number, and* `false`

*if not*.

### Solution

```
class Solution:
def isHappy(self, n: int) -> bool:
def calculate_happy(num):
sum_ = 0
# sum of square of each digit
while num:
sum_ += (num % 10) ** 2
num = num // 10
return sum_
# record
record = set()
while True:
n = calculate_happy(n)
if n == 1:
return True
# if an element repeats in set, means we are in a loop
if n in record:
return False
else:
record.add(n)
```