K Closest Points to Origin Medium

We have a list of points on the plane.  Find the K closest points to the origin (0, 0).

(Here, the distance between two points on a plane is the Euclidean distance.)

You may return the answer in any order.  The answer is guaranteed to be unique (except for the order that it is in.)

 

Input: points = [[1,3],[-2,2]], K = 1
Output: [[-2,2]]
Explanation: 
The distance between (1, 3) and the origin is sqrt(10).
The distance between (-2, 2) and the origin is sqrt(8).
Since sqrt(8) < sqrt(10), (-2, 2) is closer to the origin.
We only want the closest K = 1 points from the origin, so the answer is just [[-2,2]].

Input: points = [[3,3],[5,-1],[-2,4]], K = 2
Output: [[3,3],[-2,4]]
(The answer [[-2,4],[3,3]] would also be accepted.)

Solution:

class Solution {
    public int[][] kClosest(int[][] points, int K) {
        PriorityQueue<int[]> pq = new PriorityQueue<>((a, b) -> { return Double.compare(Math.sqrt(b[0] * b[0] + b[1] * b[1]), Math.sqrt(a[0] * a[0] + a[1] * a[1])); });
        int[][] result = new int[K][2];
        for (int[] point : points) {
            if (pq.size() < K) {
                pq.offer(point);
            } else {
                int[] largest = pq.peek();
                if (Math.sqrt(largest[0] * largest[0] + largest[1] * largest[1]) > Math.sqrt(point[0] * point[0] + point[1] * point[1])) {
                    pq.poll();
                    pq.offer(point);
                }
            }
        }
        int i = 0;
        while (pq.size() > 0) {
            result[i ++] = pq.poll();
        }
        return result;
    }
}