1828. Queries on Number of Points Inside a Circle

[antop-dev]

https://leetcode.com/problems/queries-on-number-of-points-inside-a-circle/

[antop-dev]

각 원마다 안에 포함될 수 있는 점을 먼저 필터링(녹색+파란색) 한 후, 원의 중심점과의 거리가 반지름보다 짧으면(파란색) OK!

Kotlin

class Solution {
    fun countPoints(points: Array<IntArray>, queries: Array<IntArray>): IntArray {
        return IntArray(queries.size) { i ->
            val (px, py, r) = queries[i]
            count(px, py, r, points)
        }
    }

    private fun count(qx: Int, qy: Int, radius: Int, points: Array<IntArray>): Int {
        return points.count { (px, py) ->
            px in qx - radius..qx + radius
                    && py in qy - radius..qy + radius
                    && distance(qx, qy, px, py) <= radius
        }
    }

    // 두 점의 거리 구하기
    private fun distance(qx: Int, qy: Int, px: Int, py: Int): Double {
        val xDist = px.toDouble() - qx
        val yDist = py.toDouble() - qy
        return sqrt(xDist * xDist + yDist * yDist)
    }
}

[antop-dev]

파이썬 풀이

class Solution:
    def countPoints(self, points: List[List[int]], queries: List[List[int]]) -> List[int]:
        ans = [0] * len(queries)
        for i in range(len(queries)):
            px, py, r = queries[i]
            ans[i] = self.count(px, py, r, points)
        return ans

    def count(self, qx, qy, r, points):
        count = 0
        for px, py in points:
            if qx - r <= px <= qx + r \
                    and qy - r <= py <= qy + r \
                    and self.distance(qx, qy, px, py) <= r:
                count += 1
        return count

    def distance(self, qx, qy, px, py):
        x_dist = px - qx
        y_dist = py - qy
        return math.sqrt(x_dist ** 2 + y_dist ** 2)