35 lines
692 B
Markdown
35 lines
692 B
Markdown
# 202. Happy number
|
|
|
|
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`
|