题解 | #最小的K个数#

import java.util.*;

public class Solution {
    public ArrayList<Integer> GetLeastNumbers_Solution(int [] input, int k) {
        ArrayList<Integer> res = new ArrayList<>();
        if (input == null || k < 1 || input.length < k) {
            return res;
        }
        PriorityQueue<Integer> pq = new PriorityQueue<>((a, b) -> b - a);
        for (int i = 0; i < k; i++) {
            pq.offer(input[i]);
        }
        for (int i = k; i < input.length; i++) {
            if (input[i] < pq.peek()) {
                pq.poll();
                pq.offer(input[i]);
            }
        }
        while (!pq.isEmpty()) {
            res.add(pq.poll());
        }
        Collections.reverse(res);
        return res;
    }
}