30. K_Closest_Points_to_Origin.java

class Solution {
    public int[][] kClosest(int[][] points, int K) {
        PriorityQueue<int[]> maxHeap = new PriorityQueue<>((a, b) -> (b[0]*b[0]+b[1]*b[1]) - (a[0]*a[0]+a[1]*a[1]));
        for (int[] p : points) 
        {
            maxHeap.offer(p);
            if (maxHeap.size() > K) 
            {
                maxHeap.poll();
            }
        }
        int[][] ans = new int[maxHeap.size()][2];
        int i = 0;
        while (!maxHeap.isEmpty()) {
            ans[i++] = maxHeap.poll();
        }
        return ans;
    }
}