Python heapsort (As descirbed in Introduction to Algorithms)

heapsort.py

def swap(a, i, j):
    a[i], a[j] = a[j], a[i]

def left(i):
    return 2*i + 1

def right(i):
    return 2*i + 2

def max_heapify(array, i, h_size):
    l = left(i)
    r = right(i)

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

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

    if largest != i:
        swap(array, i, largest)
        max_heapify(array, largest, h_size)

def build_max_heap(array):
    for i in reversed(range(0, int(len(array)/2))):
        max_heapify(array, i, len(array))

def heap_sort(array):
    build_max_heap(array)

    heap_size = len(array)
    for i in reversed(range(1, len(array))):
        swap(array, 0, i)
        heap_size = heap_size - 1
        max_heapify(array, 0, heap_size)


t = [5, 1, 7, 3, 6, 4, 2]
heap_sort(t)
print(t)