HeapSort.java

import java.util.*;
public class HeapSort 
{
    static void heapify(int arr[], int n, int i) 
    {
        int largest = i, left = 2 * i + 1, 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) 
        {
            int temp = arr[i];
            arr[i] = arr[largest];
            arr[largest] = temp;
            heapify(arr, n, largest);
        }
    }
    static void heapSort(int arr[]) 
    {
        int n = arr.length;
        for (int i = n / 2 - 1; i >= 0; i--) heapify(arr, n, i);

        for (int i = n - 1; i > 0; i--) 
        {
            int temp = arr[0];
            arr[0] = arr[i];
            arr[i] = temp;
            heapify(arr, i, 0);
        }
    }
    public static void main(String[] args) 
    {
        Scanner in = new Scanner(System.in);
        System.out.print("Enter number of elements: ");
        int n = in.nextInt();
        int arr[] = new int[n];
        System.out.println("Enter elements:");
        for (int i = 0; i < n; i++) arr[i] = in.nextInt();
        heapSort(arr);
        System.out.println("Sorted array:");
        for (int x : arr) System.out.print(x + " ");
        in.close();
    }
}