1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
|
class Solution:
def heapify(self, nums: [int], index: int, end: int):
left = index * 2 + 1
right = left + 1
while left <= end:
# 当前节点为非叶子节点
max_index = index
if nums[left] > nums[max_index]:
max_index = left
if right <= end and nums[right] > nums[max_index]:
max_index = right
if index == max_index:
# 如果不用交换，则说明已经交换结束
break
nums[index], nums[max_index] = nums[max_index], nums[index]
# 继续调整子树
index = max_index
left = index * 2 + 1
right = left + 1
# 初始化大顶堆
def buildMaxHeap(self, nums: [int], k: int):
# (k-2) // 2 是最后一个非叶节点，叶节点不用调整
for i in range((k - 2) // 2, -1, -1):
self.heapify(nums, i, k - 1)
return nums
def smallestK(self, arr: List[int], k: int) -> List[int]:
size = len(arr)
if k <= 0 or not arr:
return []
if size <= k:
return arr
self.buildMaxHeap(arr, k)
for i in range(k, size):
if arr[i] < arr[0]:
arr[i], arr[0] = arr[0], arr[i]
self.heapify(arr, 0, k - 1)
return arr[:k]
|