Heap Sort Python

PROGRAM TO APPLY HEAP-SORT




def heapify(arr, 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 arr[largest] < arr[l]:

        largest = l

 

    # See if right child of root exists and is

    # greater than root

    if r < n and arr[largest] < arr[r]:

        largest = r

 

    # Change root, if needed

    if largest != i:

        arr[i], arr[largest] = arr[largest], arr[i]  # swap

 

        # Heapify the root.

        heapify(arr, n, largest)

 

# The main function to sort an array of given size

 

 

def heapSort(arr):

    n = len(arr)

 

    # Build a maxheap.

    for i in range(n//2 - 1, -1, -1):

        heapify(arr, n, i)

 

    # One by one extract elements

    for i in range(n-1, 0, -1):

        arr[i], arr[0] = arr[0], arr[i]  # swap

        heapify(arr, i, 0)

 

 

# Driver code

arr = [12, 11, 13, 5, 6, 7]

heapSort(arr)

n = len(arr)

print("Sorted array is")

for i in range(n):

    print("%d" % arr[i]),

OUTPUT:

Sorted array is 
5 6 7 11 12 13 

CREDITS: https://www.geeksforgeeks.org/heap-sort/