Python Program for Heap Sort

In this article, we will learn about the solution to the problem statement given below.

Problem statement − We are given an array, we need to sort it using the concept of heapsort.

Here we place the maximum element at the end. This is repeated until the array is sorted.

Now let’s observe the solution in the implementation below−

Example

# heapify
def heapify(arr, n, i):
   largest = i # largest value
   l = 2 * i + 1 # left
   r = 2 * i + 2 # right
   # if left child exists
   if l < n and arr[i] < arr[l]:
      largest = l
   # if right child exits
   if r < n and arr[largest] < arr[r]:
      largest = r
   # root
   if largest != i:
      arr[i],arr[largest] = arr[largest],arr[i] # swap
      # root.
      heapify(arr, n, largest)
# sort
def heapSort(arr):
   n = len(arr)
   # maxheap
   for i in range(n, -1, -1):
      heapify(arr, n, i)
   # element extraction
   for i in range(n-1, 0, -1):
      arr[i], arr[0] = arr[0], arr[i] # swap
      heapify(arr, i, 0)
# main
arr = [2,5,3,8,6,5,4,7]
heapSort(arr)
n = len(arr)
print ("Sorted array is")
for i in range(n):
   print (arr[i],end=" ")

Output

Sorted array is
2 3 4 5 5 6 7 8

All the variables are declared in the local scope and their references are seen in the figure above.

Conclusion

In this article, we have learned about how we can make a Python Program for Heap Sort