<p>Given an integer array of even length <code>arr</code>, return <code>true</code><em> if it is possible to reorder </em><code>arr</code><em> such that </em><code>arr[2 * i + 1] = 2 * arr[2 * i]</code><em> for every </em><code>0 &lt;= i &lt; len(arr) / 2</code><em>, or </em><code>false</code><em> otherwise</em>.</p>

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

<pre>
<strong>Input:</strong> arr = [3,1,3,6]
<strong>Output:</strong> false
</pre>

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

<pre>
<strong>Input:</strong> arr = [2,1,2,6]
<strong>Output:</strong> false
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> arr = [4,-2,2,-4]
<strong>Output:</strong> true
<strong>Explanation:</strong> We can take two groups, [-2,-4] and [2,4] to form [-2,-4,2,4] or [2,4,-2,-4].
</pre>

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

<ul>
	<li><code>2 &lt;= arr.length &lt;= 3 * 10<sup>4</sup></code></li>
	<li><code>arr.length</code> is even.</li>
	<li><code>-10<sup>5</sup> &lt;= arr[i] &lt;= 10<sup>5</sup></code></li>
</ul>

static int io_opt = []() {
    ios::sync_with_stdio(false);
    return 0;
}();

class comp {
public:
    bool operator()(int a, int b) {
        if (abs(a) == abs(b)) {
            return a < b;
        } else {
            return abs(a) < abs(b);
        }
    }
};

class Solution {
public:
    bool insertion(vector<int> arr) {
        unordered_map<int, int> mp;
        int plus = 0, mute = 0;
        
        for(int x : arr) {
            if(mp[x] == 0) {
                mp[2*x]++;
                plus++;
            } else {
                mp[x]--;
                mute--;
            }
        }
        return !(plus + mute);
    }

    bool canReorderDoubled(vector<int>& arr) {
        vector<int> nev, pos;
        sort(arr.begin(), arr.end());

        // for(int x : arr) cout << x <<  ' ';

        for(int x : arr) {
            if(x < 0) nev.push_back(-1 * x);
            else pos.push_back(x);
        }

        reverse(nev.begin(), nev.end());

        return insertion(nev) && insertion(pos);
    }
};
70000