<p>An array is <strong>squareful</strong> if the sum of every pair of adjacent elements is a <strong>perfect square</strong>.</p>

<p>Given an integer array nums, return <em>the number of permutations of </em><code>nums</code><em> that are <strong>squareful</strong></em>.</p>

<p>Two permutations <code>perm1</code> and <code>perm2</code> are different if there is some index <code>i</code> such that <code>perm1[i] != perm2[i]</code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> nums = [1,17,8]
<strong>Output:</strong> 2
<strong>Explanation:</strong> [1,8,17] and [17,8,1] are the valid permutations.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> nums = [2,2,2]
<strong>Output:</strong> 1
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= nums.length &lt;= 12</code></li>
	<li><code>0 &lt;= nums[i] &lt;= 10<sup>9</sup></code></li>
</ul>

class Solution {
public:
    int count=0;
    bool check(int a,int b){
        int temp = sqrt(a+b);
        return ((temp*temp) == (a+b));
    }
    void help(int curr,vector<int> arr){
        if(curr>= arr.size()){
            count++;
            return ;
        }
        for(int i= curr;i<arr.size();i++){
            if(i== curr || arr[i]!= arr[curr]){
                swap(arr[curr],arr[i]);
                if(curr==0 || (curr>0 && check(arr[curr-1],arr[curr]))) help(curr+1,arr);
            }
        }
    }
    int numSquarefulPerms(vector<int>& arr) {
        sort(arr.begin(),arr.end());
        help(0,arr);
        return count;
    }
};
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