import java.util.Arrays;
import java.util.Scanner;

public class QuickSortProgram {
    public static void quickSort(int[] arr, int low, int high) {
        if (low < high) {
            int pivotIndex = partition(arr, low, high);
            System.out.println("Pivot selected: " + arr[pivotIndex]);
            System.out.println("Array after partition: " + Arrays.toString(arr));

            quickSort(arr, low, pivotIndex - 1);  // Sort left of pivot
            quickSort(arr, pivotIndex + 1, high); // Sort right of pivot
        }
    }

    private static int partition(int[] arr, int low, int high) {
        int pivot = arr[high];
        int i = low - 1;

        for (int j = low; j < high; j++) {
            if (arr[j] <= pivot) {
                i++;
                swap(arr, i, j);
            }
        }
        swap(arr, i + 1, high);
        return i + 1;
    }

    private static void swap(int[] arr, int i, int j) {
        int temp = arr[i];
        arr[i] = arr[j];
        arr[j] = temp;
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        System.out.print("Enter the number of elements in the array: ");
        int n = scanner.nextInt();
        int[] arr = new int[n];

        System.out.println("Enter the elements of the array:");
        for (int i = 0; i < n; i++) {
            arr[i] = scanner.nextInt();
        }

        System.out.println("Initial Array: " + Arrays.toString(arr));
        quickSort(arr, 0, arr.length - 1);
        System.out.println("Sorted Array: " + Arrays.toString(arr));
        
        scanner.close();
    }
}