Q:

heap sort in python

Implementation of heap sort in C:

#include <stdio.h>
int main()
{
   int heap[10], array_size, i, j, c, root, temporary;
   printf("\n Enter size of array to be sorted :");
   scanf("%d", &array_size);
   printf("\n Enter the elements of array : ");
   for (i = 0; i < array_size; i++)
      scanf("%d", &heap[i]);
   for (i = 1; i < array_size; i++)
   {
       c = i;
       do
       {
           root = (c - 1) / 2;            
           if (heap[root] < heap[c])   /* to create MAX heap array */
           {                                  // if child is greater than parent swap them
               temporary = heap[root];      // as structure is of complete binary tree
               heap[root] = heap[c];     // it took logn steps to reach from root to leaf
               heap[c] = temporary;
           }
           c = root;
       } while (c != 0);
   }
   printf("Heap array : ");
   for (i = 0; i < array_size; i++)
       printf("%d\t ", heap[i]);         //printing the heap array
   for (j = array_size - 1; j >= 0; j--)
   {
       temporary = heap[0];
       heap[0] = heap[j] ;   /* swap max element with rightmost leaf element */
       heap[j] = temporary;
       root = 0;
       do
       {
           c = 2 * root + 1;    /* left node of root element */
           if ((heap[c] < heap[c + 1]) && c < j-1)
               c++;
           if (heap[root]<heap[c] && c<j)    /* again rearrange to max heap array */
           {
               temporary = heap[root];
               heap[root] = heap[c];
               heap[c] = temporary;
           }
           root = c;
       } while (c < j);
   }
   printf("\n The sorted array is : ");
   for (i = 0; i < array_size; i++)
      printf("\t %d", heap[i]);
}
0
# Python program for implementation of heap Sort 
  
# To heapify subtree rooted at index i. 
# n is size of heap 
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[i] < 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 to test above 
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]), 
# This code is contributed by Mohit Kumra 
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