Number 447- boomerang

Number 447- boomerang

For n-tuples over a given plane, "boomerang" is represented by point for different points (i, j, k), where the distance between the distance between the i and j and k and i are equal (taking into account the sequence of tuples) .

Find the number of all boomerang. You can assume a maximum of n 500 , coordinates of all points in the closed interval [-10000, 10000] in.

Example:

输入:
[[0,0],[1,0],[2,0]]

输出:
2

解释:
两个回旋镖为 [[1,0],[0,0],[2,0]] 和 [[1,0],[2,0],[0,0]]

Source: stay button (LeetCode)
link: https://leetcode-cn.com/problems/number-of-boomerangs
copyrighted by deduction from all networks. Commercial reprint please contact the authorized official, non-commercial reprint please indicate the source.

    public int numberOfBoomerangs(int[][] points) {
        int res = 0;
        Map<Integer, Integer> map = new HashMap<>();
        for(int i = 0; i < points.length; i++) {
            map.clear();
            for(int j = 0; j < points.length; j++) {
                if(i == j) {
                    continue;
                }
                int d = getDistance(points[i], points[j]);
                int cnt = map.getOrDefault(d, 0);
                res += cnt * 2;
                map.put(d, cnt + 1);
            }
        }
        return res;
    }

    private Integer getDistance(int[] point0, int[] point1) {
        return (point0[0] - point1[0]) * (point0[0] - point1[0])
                + (point0[1] - point1[1]) * (point0[1] - point1[1]);
    }