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).
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]]
use std::collections::HashMap;implSolution{pubfnnumber_of_boomerangs(points:Vec<Vec<i32>>) -> i32{letmut len_cnt = HashMap::new();letmut ret = 0;for i in0..points.len(){for j in0..points.len(){let dx = points[i][0] - points[j][0];let dy = points[i][1] - points[j][1];*len_cnt.entry(dx * dx + dy * dy).or_insert(0) += 1;} ret += len_cnt.values().map(|v| v *(v - 1)).sum::<i32>(); len_cnt.clear();} ret }}