Python implementation of heap sort algorithm code

 
#!/usr/bin/python 
import sys 

def left_child(node): 
return node * 2 + 1 

def right_child(node): 
return node * 2 + 2 

def parent(node): 
if (node % 2): 
return (i - 1) / 2 
else: 
return (i - 2) / 2 

def max_heapify(array, i, heap_size): 
l = left_child(i) 
r = right_child(i) 

largest = i 
if l < heap_size and array[l] > array[i]: 
largest = l 

if r < heap_size and array[r] > array[largest]: 
largest = r 

if largest != i: 
array[i], array[largest] = array[largest], array[i] 
max_heapify(array, largest, heap_size) 

def build_max_heap(array): 
for i in range(len(array) / 2, -1, -1): 
max_heapify(array, i, len(array)) 


def heap_sort(array): 
build_max_heap(array) 
for i in range(len(array) - 1, 0, -1): 
array[0], array[i] = array[i], array[0] 
max_heapify(array, 0, i) 


if __name__ == "__main__": 
array = [0, 2, 6, 98, 34, -5, 23, 11, 89, 100, 7] 
heap_sort(array) 

for a in array: 
sys.stdout.write("%d " % a)