Another method for heap sort

[scottwar34]

Good code, you could also use this approach to the heap sort algorithm:

public class HeapSort
{
public void sort(int arr[])
{
int n = arr.length;

            // 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
                    int temp = arr[0];
                    arr[0] = arr[i];
                    arr[i] = temp;

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

    // 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)
            {
                    int swap = arr[i];
                    arr[i] = arr[largest];
                    arr[largest] = swap;

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

    /* A utility function to print array of size n */
    static void printArray(int arr[])
    {
            int n = arr.length;
            for (int i=0; i<n; ++i)
                    System.out.print(arr[i]+" ");
            System.out.println();
    }

    // Driver program
    public static void main(String args[])
    {
            int arr[] = {12, 11, 13, 5, 6, 7};
            int n = arr.length;

            HeapSort ob = new HeapSort();
            ob.sort(arr);

            System.out.println("Sorted array is");
            printArray(arr);
    }

}