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]]
class Solution { public int numberOfBoomerangs(int[][] points) { int res = 0; for(int i = 0; i < points.length; i++){ Map<Integer, Integer> map = new HashMap(); for(int j = 0; j < points.length; j++){ if(i == j) continue; int k = help(points[i], points[j]); map.put(k, (map.getOrDefault(k, 0)) + 1); } for(int t: map.values()) res += t*(t-1); } return res; } public int help(int[] a, int[] b){ int t1 = a[0] - b[0]; int t2 = a[1] - b[1]; return t1*t1 + t2*t2; } }