Problem URL: Number of boomerangs

We will use a hashmap to store the distance between each point and the current point. Then we will iterate through the hashmap to calculate the number of boomerangs.

class Solution:
    def numberOfBoomerangs(self, points: List[List[int]]) -> int:
        def distance(p1, p2):
            return (p1[0] - p2[0]) ** 2 + (p1[1] - p2[1]) ** 2

        res = 0
        for p1 in points:
            hashmap = {}
            for p2 in points:
                d = distance(p1, p2)
                hashmap[d] = hashmap.get(d, 0) + 1
            for d in hashmap:
                res += hashmap[d] * (hashmap[d] - 1)
        return res

Time complexity: O(n^2)
Space complexity: O(n)