面试题 17.14. 最小K个数

设计一个算法，找出数组中最小的k个数。以任意顺序返回这k个数均可。

示例：

输入： arr = [1,3,5,7,2,4,6,8], k = 4
输出： [1,2,3,4]
提示：

0 <= len(arr) <= 100000
0 <= k <= min(100000, len(arr))

来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/smallest-k-lcci

import heapq
class Solution:
    def smallestK(self, arr: List[int], k: int) -> List[int]:
        if k>len(arr) or k==0:
            return []
        heap = []
        for i in arr[:k]:
            heapq.heappush(heap,-i)
        for i in arr[k:]:
            if i<-heap[0]:
                heapq.heappop(heap)
                heapq.heappush(heap,-i)
        res = []
        for i in range(k):
            res.append(-heapq.heappop(heap))
        return res[::-1]