#526
Beautiful Arrangement
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Description
Consider all permutations of the integers 1 through n. A permutation perm (1-indexed) is called beautiful when, for every index i (1 <= i <= n), at least one of these conditions holds:
- perm[i] is evenly divisible by i.
- i is evenly divisible by perm[i].
Given n, count and return the total number of beautiful arrangements.
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
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