# [202. Happy Number](https://leetcode.com/problems/happy-number) [中文文档](/solution/0200-0299/0202.Happy%20Number/README.md) ## 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.

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`
## Solutions ### **Python3** ```python class Solution: def isHappy(self, n: int) -> bool: def get_next(n): s = 0 while n > 0: n, digit = divmod(n, 10) s += digit ** 2 return s visited = set() while n != 1 and n not in visited: visited.add(n) n = get_next(n) return n == 1 ``` ### **Java** ```java class Solution { public boolean isHappy(int n) { Set visited = new HashSet<>(); while (n != 1 && !visited.contains(n)) { visited.add(n); n = getNext(n); } return n == 1; } private int getNext(int n) { int s = 0; while (n > 0) { int digit = n % 10; s += digit * digit; n /= 10; } return s; } } ``` ### **...** ``` ```