Heap_Sort.c

#include<stdio.h>

void swap(int *a, int *b)
{
    int temp = *a;
    *a = *b;
    *b = temp;
}

void heapify(int arr[], int n, int i){
    int largest = i;
    int left = 2*i + 1;
    int right = 2*i + 2;

    if(left < n && arr[left] > arr[largest]){
        largest = left;
    }
    if(right < n && arr[right] > arr[largest]){
        largest =  right;
    }
    if(largest != i){
        swap(&arr[i], &arr[largest]);
        heapify(arr, n, largest);
    }
}

void heapSort(int arr[], int n){
    for(int i = n/2; i >= 0; i--){
        heapify(arr, n, i);
    }
    for(int i = n - 1; i >=  0; i--){
        swap(&arr[0], &arr[i]);
        heapify(arr, i, 0);
    }
}

void printArray(int arr[], int n)
{
    for (int i = 0; i < n; i++)
    {
        printf("%d ", arr[i]);
    }
} 

int main(){
    int arr[] = {12, 5, 7, 9, 16, 20};
    int n = sizeof(arr)/sizeof(arr[0]);
    heapSort(arr, n);
    printArray(arr, n);
    return 0;
}