I have to say `stream`

in Java8 is a good thing!

```
public class Solution {
public int numberOfBoomerangs(int[][] points) {
int ans=0, n=points.length;
for (int i=0;i<n;i++) {
HashMap<Integer, Integer> map=new HashMap<>();
for (int j=0;j<n;j++) {
int distance=(points[i][0]-points[j][0])*(points[i][0]-points[j][0])+(points[i][1]-points[j][1])*(points[i][1]-points[j][1]);
map.put(distance, map.getOrDefault(distance, 0)+1);
}
ans+=map.values().stream().mapToInt(x -> x*(x-1)).sum();
}
return ans;
}
}
```