题目：

题解：

func numberOfBoomerangs(points [][]int) (ans int) {
    for _, p := range points {
        cnt := map[int]int{}
        for _, q := range points {
            dis := (p[0]-q[0])*(p[0]-q[0]) + (p[1]-q[1])*(p[1]-q[1])
            cnt[dis]++
        }
        for _, m := range cnt {
            ans += m * (m - 1)
        }
    }
    return
}