QuickSort.java

public class QuickSort {   
 
    // Method to perform the Quick Sort    
    public static void quickSort(int[] arr, int low, int high) {   
        if (low < high) {  
            // Partition the array and get the pivot index  
            int pivotIndex = partition(arr, low, high);
   
            // Recursively sort the elements before and after partition
            quickSort(arr, low, pivotIndex - 1);
            quickSort(arr, pivotIndex + 1, high);
        } 
    }
 
    // Method to partition the array into two halves
    private static int partition(int[] arr, int low, int high) {
        // Choose the rightmost element as the pivot
        int pivot = arr[high];
        int i = low - 1; // Index of smaller element

        for (int j = low; j < high; j++) {
            // If the 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 the pivot element to its correct position
        int temp = arr[i + 1];
        arr[i + 1] = arr[high];
        arr[high] = temp;

        return i + 1; // Return the pivot index
    }

    // Method to print the array
    private static void printArray(int[] arr) {
        for (int num : arr) {
            System.out.print(num + " ");
        }
        System.out.println();
    }

    // Main method to test the Quick Sort implementation
    public static void main(String[] args) {
        int[] array = {10, 7, 8, 9, 1, 5};

        System.out.println("Original array:");
        printArray(array);

        quickSort(array, 0, array.length - 1);
        System.out.println("Sorted array:");
        printArray(array);
    }
}