leetcode

0447.cpp (697B)

 class Solution {
     static int distance(const vector<int> &a, const vector<int> &b) {
         return pow(b[0] - a[0], 2) + pow(b[1] - a[1], 2);
     }
 
   public:
     int numberOfBoomerangs(const vector<vector<int>> &points) const {
         const int n = size(points);
         int res = 0;
 
         for (int i = 0; i < n; i++) {
             unordered_map<int, int> um;
 
             for (int j = 0; j < n; j++) {
                 if (i == j) continue;
                 um[distance(points[i], points[j])]++;
             }
 
             for (const auto [_, cnt] : um) {
                 if (cnt == 1) continue;
                 res += cnt * (cnt - 1);
             }
         }
 
         return res;
     }
 };