Formatted question description: https://leetcode.ca/all/1828.html

# 1828. Queries on Number of Points Inside a Circle

## Level

Medium

## Description

You are given an array `points`

where `points[i] = [x_i, y_i]`

is the coordinates of the `i-th`

point on a 2D plane. Multiple points can have the **same** coordinates.

You are also given an array `queries`

where `queries[j] = [x_j, y_j, r_j]`

describes a circle centered at `(x_j, y_j)`

with a radius of `r_j`

.

For each query `queries[j]`

, compute the number of points **inside** the `j-th`

circle. Points **on the border** of the circle are considered **inside**.

Return *an array answer, where answer[j] is the answer to the j-th query*.

**Example 1:**

**Input:** points = [[1,3],[3,3],[5,3],[2,2]], queries = [[2,3,1],[4,3,1],[1,1,2]]

**Output:** [3,2,2]

**Explanation:** The points and circles are shown above.

queries[0] is the green circle, queries[1] is the red circle, and queries[2] is the blue circle.

**Example 2:**

**Input:** points = [[1,1],[2,2],[3,3],[4,4],[5,5]], queries = [[1,2,2],[2,2,2],[4,3,2],[4,3,3]]

**Output:** [2,3,2,4]

**Explanation:** The points and circles are shown above.

queries[0] is green, queries[1] is red, queries[2] is blue, and queries[3] is purple.

**Constraints:**

`1 <= points.length <= 500`

`points[i].length == 2`

`0 <= x_i, y_i <= 500`

`1 <= queries.length <= 500`

`queries[j].length == 3`

`0 <= x_j, y_j <= 500`

`1 <= r_j <= 500`

- All coordinates are integers.

## Solution

For each query, obtain the values `x`

, `y`

and `r`

, and for each point, calculate the squared distance between the query’s center and the point. If the squared distance is less than or equal to `r * r`

, then the point is inside the circle. The number of points inside each circle can be calculated.

```
class Solution {
public int[] countPoints(int[][] points, int[][] queries) {
int queriesCount = queries.length;
int[] counts = new int[queriesCount];
for (int i = 0; i < queriesCount; i++) {
int[] query = queries[i];
int x = query[0], y = query[1], r = query[2];
int rSquare = r * r;
for (int[] point : points) {
int distanceSquare = getDistanceSquare(point, x, y);
if (distanceSquare <= rSquare)
counts[i]++;
}
}
return counts;
}
public int getDistanceSquare(int[] point, int x, int y) {
return (x - point[0]) * (x - point[0]) + (y - point[1]) * (y - point[1]);
}
}
```