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 || input.length < 1 || input.length < k) {
            return res;
        }
        if (k < 1) {
            return res;
        }
        int n = input.length;
        PriorityQueue<Integer> pq = new PriorityQueue<>((o1, o2) -> o2 - o1);
        for (int i = 0; i < n; i++) {
            if (i < k) {
                pq.offer(input[i]);
            } else if (pq.peek() > input[i]) {
                pq.poll();
                pq.offer(input[i]);
            }
        }
        
        while (!pq.isEmpty()) {
            res.add(pq.poll());
        }
        return res;
    }
}