堆排序——python实现

   关于堆排序的详细讲解过程，见：http://www.cnblogs.com/MOBIN/p/5374217.html

  下面是python 实现：

def max_head(mylist, headsize, root_index):
    left = root_index*2+1
    right =root_index*2+2
    large_index = root_index
    if left < headsize and mylist[left] > mylist[large_index]:
        large_index = left
    if right < headsize and mylist[right] > mylist[large_index]:
        large_index =right
    if large_index != root_index:
        mylist[large_index], mylist[root_index] =mylist[root_index], mylist[large_index]
        max_head(mylist, headsize, large_index)

def create_head(mylist):
    length = len(mylist)
    max_child_index = (length - 2)//2
    for i in range(max_child_index, -1, -1):
        max_head(mylist, length, i)

def sort_head(mylist):
    create_head(mylist)
    for i in range(len(mylist)-1,-1,-1):
        mylist[0], mylist[i] = mylist[i], mylist[0]
        max_head(mylist, i, 0)

if __name__== "__main__":
    mylist = [49,38,65,97,76,13,27,49]
    sort_head(mylist)
    print mylist