Quick Sort 17226

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

class QuickSort {
    /* This function takes last element as pivot,
       places the pivot element at its correct
       position in sorted array, and places all
       smaller (smaller than pivot) to left of
       pivot and all greater elements to right
       of pivot */
    int partition(int arr[], int low, int high) {
        int pivot = arr[high];
        int i = (low - 1); // index of smaller element
        for (int j = low; j < high; j++) {
            // If current element is smaller than the pivot
            if (arr[j] < pivot) {
                i++;

                // swap arr[i] and arr[j]
                int temp = arr[i];
                arr[i] = arr[j];
                arr[j] = temp;
            }
        }

        // swap arr[i+1] and arr[high] (or pivot)
        int temp = arr[i + 1];
        arr[i + 1] = arr[high];
        arr[high] = temp;

        return i + 1;
    }


    /* The main function that implements QuickSort()
      arr[] --> Array to be sorted,
      low  --> Starting index,
      high  --> Ending index */
    void sort(int arr[], int low, int high) {
        if (low < high) {
            /* pi is partitioning index, arr[pi] is
              now at right place */
            int pi = partition(arr, low, high);

            // Recursively sort elements before
            // partition and after partition
            sort(arr, low, pi - 1);
            sort(arr, pi + 1, high);
        }
    }

    // Driver program
    public static void main(String args[]) {
        Scanner scan = new Scanner(System.in);
        int N = 0;

        System.out.printf("Input the number of elements N : "); // Input the number of elements in the array
        N = scan.nextInt();

        int arr[] = new int[N];

        for (int i = 0; i < N; i++) {
            System.out.printf("Please input the [%d] element : ", i); // Input the elements of the array
            arr[i] = scan.nextInt();
        }

        System.out.println();
        System.out.println("Array Before Quick Sort : ");

        System.out.println("Array: " + Arrays.toString(arr)); // Print the array before Quick Sort
        System.out.println();

            QuickSort ob = new QuickSort();
            ob.sort(arr, 0, N - 1);

        System.out.println();

        System.out.println("Array After Quick Sort : ");
        System.out.println("Array: " + Arrays.toString(arr)); // Print the array after Quick Sort
        System.out.println();
        }
    }