Add head_sort.cpp

#include <iostream>
using namespace std;

void heapify(int arr[], int N, int i)
{

	int largest = i;

	int l = 2 * i + 1;

	int r = 2 * i + 2;

	if (l < N && arr[l] > arr[largest])
		largest = l;

	if (r < N && arr[r] > arr[largest])
		largest = r;

	if (largest != i) {
		swap(arr[i], arr[largest]);

		heapify(arr, N, largest);
	}
}

void heapSort(int arr[], int N)
{

	for (int i = N / 2 - 1; 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)
		cout << arr[i] << " ";
	cout << "\n";
}

int main()
{
	int N;
	cout << "Enter the size of array" << endl;
	cin >> N;
	int arr[N];
	for (int i = 0; i < N; ++i)
	{
		cin >> arr[i];
	}

	heapSort(arr, N);

	cout << "Sorted array is \n";
	printArray(arr, N);
}