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Java-based LeetCode algorithm problem solutions, regularly updated
526\. Beautiful Arrangement
Medium
Suppose you have `n` integers labeled `1` through `n`. A permutation of those `n` integers `perm` (**1-indexed**) is considered a **beautiful arrangement** if for every `i` (`1 <= i <= n`), **either** of the following is true:
* `perm[i]` is divisible by `i`.
* `i` is divisible by `perm[i]`.
Given an integer `n`, return _the **number** of the **beautiful arrangements** that you can construct_.
**Example 1:**
**Input:** n = 2
**Output:** 2
**Explanation:**
The first beautiful arrangement is [1,2]:
- perm[1] = 1 is divisible by i = 1
- perm[2] = 2 is divisible by i = 2
The second beautiful arrangement is [2,1]:
- perm[1] = 2 is divisible by i = 1
- i = 2 is divisible by perm[2] = 1
**Example 2:**
**Input:** n = 1
**Output:** 1
**Constraints:**
* `1 <= n <= 15`