<p>You are given <code>n</code> <code>points</code> in the plane that are all <strong>distinct</strong>, where <code>points[i] = [x<sub>i</sub>, y<sub>i</sub>]</code>. A <strong>boomerang</strong> is a tuple of points <code>(i, j, k)</code> such that the distance between <code>i</code> and <code>j</code> equals the distance between <code>i</code> and <code>k</code> <strong>(the order of the tuple matters)</strong>.</p>

<p>Return <em>the number of boomerangs</em>.</p>

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

<pre>
<strong>Input:</strong> points = [[0,0],[1,0],[2,0]]
<strong>Output:</strong> 2
<strong>Explanation:</strong> The two boomerangs are [[1,0],[0,0],[2,0]] and [[1,0],[2,0],[0,0]].
</pre>

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

<pre>
<strong>Input:</strong> points = [[1,1],[2,2],[3,3]]
<strong>Output:</strong> 2
</pre>

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

<pre>
<strong>Input:</strong> points = [[1,1]]
<strong>Output:</strong> 0
</pre>

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

<ul>
	<li><code>n == points.length</code></li>
	<li><code>1 &lt;= n &lt;= 500</code></li>
	<li><code>points[i].length == 2</code></li>
	<li><code>-10<sup>4</sup> &lt;= x<sub>i</sub>, y<sub>i</sub> &lt;= 10<sup>4</sup></code></li>
	<li>All the points are <strong>unique</strong>.</li>
</ul>

class Solution {
public:

    int cal(vector<int> a, vector<int> b) {
        return (a[0] - b[0])*(a[0] - b[0]) + (a[1] - b[1]) * (a[1] - b[1]);
    }
    int numberOfBoomerangs(vector<vector<int>>& points) {
        int n = points.size();

        vector<vector<int>> dist(n, vector<int> (n, 0));

        for(int i = 0; i < n; i++) {
            for(int j = i + 1; j < n; j++) {
                int dis = cal(points[i], points[j]);
                dist[i][j] = dis;
                dist[j][i] = dis;
            }
        }
        
        int ans = 0;
        for(int i = 0; i < n; i++) {
            vector<int> diss = dist[i];
            sort(diss.begin(), diss.end());
            int cnt = 1, prev = diss[0];
            for(int j = 1; j < n; j++) {
                if(diss[j] == prev) {
                    cnt++;
                }
                else {
                    ans += cnt * (cnt - 1);
                    cnt = 1;
                    prev = diss[j];
                }
            }
            cout << cnt << endl;
            ans += cnt * (cnt - 1);
        }

        return ans;
    }
};
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