Heap-Sort.c

/*  Below program is written in C language  */
# include <stdio.h>

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

    // if left child is larger than root
    if (l < n && arr[l] > arr[largest])
        largest = l;

    // if right child is larger than the largest so far
    if (r < n && arr[r] > arr[largest])
        largest = r;

    // if largest is not root
    if (largest != i)
    {
        swap(arr[i], arr[largest]);


 	// recursively heapify the affected sub-tree
        heapify(arr, n, largest);
    }
}

void heapSort(int arr[], int n)
{
    // build heap (rearrange array)
    for (int i = n / 2 - 1; i >= 0; i--)
        heapify(arr, n, i);

    // one by one extract an element from heap
    for (int i=n-1; i>=0; i--)
    {
        // move current root to end
        swap(arr[0], arr[i]);

        // call max heapify on the reduced heap
        heapify(arr, i, 0);
    }
}

// function to print the array of given size
void printArray(int a[], int size)
{
    int i;
    for (i=0; i < size; i++)
    {
        printf("%d ", a[i]);
    }
    printf("\n");
}

int main()
{
    int arr[] = {121, 10, 130, 57, 36, 17};
    int n = sizeof(arr)/sizeof(arr[0]);

    heapSort(arr, n);

    printf( "Sorted array is \n");
    printArray(arr, n);
}