题解 | #最小的K个数# -- 优先队列

import java.util.ArrayList;
import java.util.Comparator;
import java.util.PriorityQueue;

public class Solution {
    public ArrayList<Integer> GetLeastNumbers_Solution(int [] input, int k) {
        if (k == 0) {
            return new ArrayList<>();
        }
        PriorityQueue<Integer> maxHeap = new PriorityQueue<Integer>
        (k, new Comparator<Integer>() {
            @Override
            public int compare(Integer o1, Integer o2) {
                return o2.compareTo(o1);
            }
        });

        for (Integer i : input)  {
            if (maxHeap.size() < k) {
                maxHeap.add(i);
            } else {
                if (maxHeap.peek() > i) {
                    maxHeap.remove();
                    maxHeap.add(i);
                }
            }
        }
        ArrayList<Integer> result = new ArrayList<>();
        while(maxHeap.size() > 0) {
            result.add(maxHeap.remove());
        }
        return result;
    }

}