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 until the number equals 1 (where it will stay), or it **loops endlessly in a cycle** not including 1.
- 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 → ... → 1
```
**Example 2:**
```
Input: n = 2
Output: false
```