Number of Squareful Arrays

arrayhash tablemath

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: 1

1 <= nums.length <= 12

0 <= nums[i] <= 10 ^9

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Hard

Difficulty

Topic Info

ModuleDSA

CategoryArray

Sub-topicHash Table