JeLuOrRi/heap.py

''' Luis Andrés López Mañán
    Program written by hand as a draft on 09/19/2022
    Credit goes to GeeksForGeeks
    Link: https://www.geeksforgeeks.org/python-program-for-heap-sort/
    Last access on 09/19/2022
    Program wrriten and edited on 10/10/2022
'''

# Python program for implementation of heap Sort (Part I)

# This function heapifies a subtree rooted at an index
# i. Also, n is the size of a heap and arr is array.

def heapify(lista, n, i):
	largest = i # Initialize largest as root
	l = 2 * i + 1 # left = 2*i + 1
	r = 2 * i + 2 # right = 2*i + 2

# See if left child of root exists and is
# greater than root

	if l < n and lista[i] < lista[l]:
		largest = l

# See if right child of root exists and is
# greater than root

	if r < n and lista[largest] < lista[r]:
		largest = r

# Change root, if needed

	if largest != i:
		(lista[i], lista[largest]) = (lista[largest], lista[i]) # swap

# Heapify the root.

		heapify(lista, n, largest)