Heap Sort

// C++ program for implementation of Heap Sort
#include <iostream>
using namespace std;

// To heapify a subtree rooted with node i which is
// an index in arr[]. n is size of heap
void heapify(int arr[], int n, int i)
{

    int largest = i;  // Initialize largest as root
    int l = 2*i + 1;  // left = 2*i + 1
    int r = 2*i + 2;  // right = 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 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]);
    //which ever is large left or right from ROOT will be swap by ROOT
    //a[i] is root,a[largest] is left or right node value.
   

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

// main function to build max heap
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 k=n-1;k>=0;k--)
    {
        // Move Root  Node to end
        swap(arr[0], arr[k]);
        // call max heapify on the reduced heap
        heapify(arr, k, 0);
    }
}

/* A utility function to print array of size n */
void printArray(int arr[], int n)
{
    for (int i=0; i<n; ++i)
        cout << arr[i] << " ";
    cout << "\n";
}

// Driver program
int main()
{
    int arr[] = {50,75,60,35,45,25,95};
    int n = sizeof(arr)/sizeof(arr[0]); 
    heapSort(arr, n);

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