heapsort.c

#include <stdio.h>
  
  void swap(int *a, int *b) {
    int tmp = *a;
    *a = *b;
    *b = tmp;
  }
  
  void heapify(int arr[], int n, int i) {
    int max = i; //Initialize max as root
    int leftChild = 2 * i + 1;
    int rightChild = 2 * i + 2;
  
    //If left child is greater than root
    if (leftChild < n && arr[leftChild] > arr[max])
      max = leftChild;
  
    //If right child is greater than max
    if (rightChild < n && arr[rightChild] > arr[max])
      max = rightChild;
  
    //If max is not root
    if (max != i) {
      swap(&arr[i], &arr[max]);
      //heapify the affected sub-tree recursively
      heapify(arr, n, max);
    }
  }

  //Main function to perform heap sort
  void heapSort(int arr[], int n) {
    //Rearrange array (building heap)
    for (int i = n / 2 - 1; i >= 0; i--)
      heapify(arr, n, i);
 
    //Extract elements from heap one by one
    for (int i = n - 1; i >= 0; i--) {
      swap(&arr[0], &arr[i]); //Current root moved to the end
  
      heapify(arr, i, 0); //calling max heapify on the heap reduced
    }
  }

  //print size of array n using utility function
  void display(int arr[], int n) {
    for (int i = 0; i < n; ++i)
      printf("%d ", arr[i]);
    printf("\n");
  }

  //Driver code
  int main() {
    int arr[100],m;
    printf("enter array size");
    scanf("%d",&m);
    printf("enter array elements")
     for(i=0;i<m:i++)
       scanf("%d",&arr[i]);
    int n = sizeof(arr) / sizeof(arr[0]);
	
    printf("Original array:\n");
    display(arr, n);
    heapSort(arr, n);
  
    printf("Sorted array:\n");
    display(arr, n);
  }