Given n points in the plane that are all pairwise distinct, a "boomerang" is
a tuple of points (i, j, k) such that the distance between i and
j equals the distance between i and k (the order
of the tuple matters).
Find the number of boomerangs. You may assume that n will be at most 500 and coordinates of points are all in the range [-10000, 10000] (inclusive).
Example:
Input: [[0,0],[1,0],[2,0]] Output: 2 Explanation: The two boomerangs are [[1,0],[0,0],[2,0]] and [[1,0],[2,0],[0,0]]