- Difficulty: Medium
- Tags: LeetCode, Medium, Bit Manipulation, Array, Bitmask, leetcode-2741, Backtracking, O(n^2 * 2^n), O(n * 2^n), Memoization, Dynamic Programming
Problem
You are given a 0-indexed integer array nums
containing n
distinct positive integers. A permutation of nums
is called special if:
- For all indexes
0 <= i < n - 1
, eithernums[i] % nums[i+1] == 0
ornums[i+1] % nums[i] == 0
.
Return the total number of special permutations. As the answer could be large, return it modulo 109 + 7
.
Example 1:
Input: nums = [2,3,6] Output: 2 Explanation: [3,6,2] and [2,6,3] are the two special permutations of nums.
Example 2:
Input: nums = [1,4,3] Output: 2 Explanation: [3,1,4] and [4,1,3] are the two special permutations of nums.
Constraints:
2 <= nums.length <= 14
1 <= nums[i] <= 109