# 202. Happy Number

#### Easy

***

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*.

 

**Example 1:**

```
Input: n = 19
Output: true
Explanation:
12 + 92 = 82
82 + 22 = 68
62 + 82 = 100
12 + 02 + 02 = 1
```

**Example 2:**

```
Input: n = 2
Output: false
```

 

**Constraints:**

* `1 <= n <= 231 - 1`

```python
class Solution:
    def isHappy(self, n: int) -> bool:
        d = {}
        num = n
        while num != 1:
            if num not in d:
                d[num] = 1
            else:
                return False
            sum_ = 0
            for digit in str(num):
                sum_ += pow(int(digit), 2)
            num = sum_
        return True
            
```