LeetCode117|最小的k个数

示例 1：

输入：arr = [3,2,1], k = 2
输出：[1,2] 或者 [2,1]
示例 2：

输入：arr = [0,1,2,1], k = 1
输出：[0]
 

限制：

0 <= k <= arr.length <= 10000
0 <= arr[i] <= 10000

import java.util.Arrays;
import java.util.Collections;
import java.util.PriorityQueue;
import java.util.Queue;

public class GetLeastNumbersTest {
    public static void main(String[] args) {
        int[] arr = {4, 5, 1, 6, 2, 7, 3, 8};
        int k = 4;
        int[] leastNumbers = getLeastNumbers2(arr, k);
        for (int num : leastNumbers
        ) {
            System.out.print(num + "t");
        }
    }

    public static int[] getLeastNumbers(int[] arr, int k) {
        if (arr == null || k == 0) {
            return new int[0];
        }
        Queue<Integer> queue = new PriorityQueue<>((o1, o2) -> o2 - o1);
        for (int num : arr) {
            if (queue.size() < k) {
                queue.offer(num);
            } else if (queue.peek() > num) {
                queue.poll();
                queue.offer(num);
            }
        }
        int[] result = new int[k];

        for (int i = 0; i < k; i++) {
            result[i] = queue.poll();
        }
        return result;

    }

    public static int[] getLeastNumbers2(int[] arr, int k) {
        if (arr == null || arr.length < k) {
            return new int[0];
        }
        Arrays.sort(arr);
        int[] result = new int[k];
        if (k >= 0) {
            System.arraycopy(arr, 0, result, 0, k);
        }
        return result;
    }
}