Number of Squareful Arrays
An array is squareful if the sum of every pair of adjacent elements is a perfect square.
Given an integer array nums, return the number of permutations of nums that are squareful.
Two permutations perm1 and perm2 are different if there is some index i such that perm1[i] != perm2[i].
Example 1
Input
nums = [1,17,8]Output
2[1,8,17] and [17,8,1] are the valid permutations.
Example 2
Input
nums = [2,2,2]Output
1All elements are the same, so there is only one distinct squareful permutation.
Constraints
- 1 <= nums.length <= 12
- 0 <= nums[i] <= 10^9