标签：color point mos att 含义 nbsp oom i++ tin
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 iand 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]]
题目含义：定义一种类似“回形标”的三元组结构，即在三元组(i, j, k)中i和j之间的距离与i和k之间的距离相等。找到一组坐标数据中，可构成几组这样的“回形标”结构。
1 private int getDistance(int[] p1, int[] p2) { 2 int x = p1[0] - p2[0]; 3 int y = p1[1] - p2[1]; 4 return x * x + y * y; 5 } 6 7 public int numberOfBoomerangs(int[][] points) { 8 if (points.length == 0 || points[0].length == 0) return 0; 9 int result = 0; 10 for (int i = 0; i < points.length; i++) { 11 Map<Integer, Integer> distances = new HashMap<>(); 12 for (int j = 0; j < points.length; j++) { 13 if (i == j) continue; 14 int distance = getDistance(points[i], points[j]); 15 distances.put(distance, distances.getOrDefault(distance, 0) + 1); 16 } 17 for (Integer count : distances.values()) { 18 result += count * (count - 1); //只有大于两条的才能有值.count个节点距离都相等，任选两条就可以与其它边一起构成会回形标。所以可以构成count * (count - 1)条 19 } 20 } 21 return result; 22 }
标签：color point mos att 含义 nbsp oom i++ tin
原文地址：http://www.cnblogs.com/wzj4858/p/7718710.html
