447

class Solution {
public:
    int numberOfBoomerangs(vector<vector<int>>& points) {
        int res = 0;
        // iterate over all the points
        for (int i = 0; i < points.size(); ++i) {
            unordered_map<long, int> m;
            // iterate over all points other than points[i]
            for (int j = 0; j < points.size(); ++j) {
                if (j == i) continue;
                int dy = points[i][1] - points[j][1];
                int dx = points[i][0] - points[j][0];
                // compute squared euclidean distance from points[i]
                int dist = dy*dy+dx*dx;
                m[dist]++;
            }
            // Update answer
            for(auto& p : m)
                if(p.second > 1)
                    res += p.second * (p.second - 1);
        }
        return res;
    }
};