python实现堆排序的三种方式

# -*- coding: utf-8 -*-
"""
Created on Fri May 16 14:57:50 2014

@author: lifeix
"""
import heapq
#堆排序
#第一种实现
def Heapify(a, start, end):
left = 0
right = 0
maxv = 0
left = start * 2
right = start * 2 + 1
while left <= end:
maxv = left
if right <= end:
if a[left] < a[right]:
maxv = right
else:
maxv = left
if a[start] < a[maxv]:
a[maxv],a[start] = a[start],a[maxv]
start = maxv
else:
break
left = start * 2
right = start * 2 + 1

def BuildHeap(a):
size = len(a)
i = (size -1) // 2;
while i >= 0:
Heapify(a, i, size - 1)
i = i - 1

def HeapSort(a):
BuildHeap(a)
print 'first before sorted:', a
i = len(a) - 1

while i >= 0:
a[0],a[i] = a[i],a[0]
Heapify(a, 0, i - 1)
i = i - 1

a = [4,1,3,2,16,9,10,14,8,7]
HeapSort(a)
print 'first after sorted',a

#第二种实现
def buildHeap(a,size):
for j in range(size/2 - 1, -1,-1):
adjustHeap(a,j,size)

def adjustHeap(a, i, size):
lchild = 2*i  #i的左孩子节点序号
rchild = 2*i + 1 #i的右孩子节点序号
maxIndex = i
if i < size/2:
if lchild <= size and a[lchild] > a[maxIndex]:
maxIndex = lchild
if rchild <= size and a[rchild] > a[maxIndex]:
maxIndex = rchild
if maxIndex != i:
a[i],a[maxIndex] = a[maxIndex], a[i]
adjustHeap(a, maxIndex,size)

if __name__ == "__main__":
a =[4,1,3,2,16,9,10,14,8,7]
b =[4,1,3,2,16,9,10,14,8,7]
buildHeap(a, len(a))
print '-------------------------------------------------'
print 'second before sorted',a
i = len(a) - 1
while i >= 0:
a[0],a[i] = a[i],a[0]
buildHeap(a,i)
i = i - 1
print 'second after sorted',a

#python自带函数实现
heapq.heapify(b)
heap = []
while b:
heap.append(heapq.heappop(b))
b[:] = heap
print '-------------------------------------------------'
print 'sdk sorted',b