# 堆排序,利用堆进行排序
# 堆是一种完全二叉树,分为大根堆、小根堆
# 大根堆:每个父节点大于等于子节点;小根堆:每个父节点小于等于子节点
# 算法原理(升序):
# 1.构造大根堆
# 2.将堆顶点与最右下进行交换(最值右移)
# 3.除最右下值(最大值)外,构造大根堆
# 4.重复实现升序
# 实现过程:
#参考 https://blog.csdn.net/minxihou/article/details/51850001
import random
def MAX_Heapify(heap,HeapSize,root): #在堆中做结构调整使得父节点的值大于子节点
left = 2*root + 1
right = left + 1
larger = root
if left < HeapSize and heap[larger] < heap[left]:
larger = left
if right < HeapSize and heap[larger] < heap[right]:
larger = right
if larger != root: #如果做了堆调整则larger的值等于左节点或者右节点的,这个时候做对调值操作
heap[larger],heap[root] = heap[root],heap[larger]
MAX_Heapify(heap, HeapSize, larger)
def Build_MAX_Heap(heap): #构造一个堆,将堆中所有数据重新排序
HeapSize = len(heap) #将堆的长度当独拿出来方便
for i in range((HeapSize -2)//2,-1,-1):#从后往前出数
MAX_Heapify(heap,HeapSize,i)
def HeapSort(heap):
Build_MAX_Heap(heap)
for i in range(len(heap)-1,-1,-1): #将根节点取出与最后一位做对调,对前面len-1个节点继续进行对调整过程。
heap[0],heap[i] = heap[i],heap[0]
MAX_Heapify(heap, i, 0)
return heap
if __name__ == '__main__':
Range = 100
Length = 11
list = random.sample(range(Range), Length) # 在指定序列中随机获取指定长度片段
print('before sort:', list)
HeapSort(list)
print('after sort:', list)
python算法9.12——堆排序
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转载自blog.csdn.net/nominior/article/details/82669401
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