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 Explanation: [1,8,17] and [17,8,1] are the valid permutations.
Example 2:
Input: nums = [2,2,2] Output: 1
Constraints:
1 <= nums.length <= 120 <= nums[i] <= 109
[Array] [Math] [Dynamic Programming] [Backtracking] [Bit Manipulation] [Bitmask]
- Permutations II (Medium)