QuickSort.java

package day29;
public class QuickSort {
    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 (arr[j] < pivot) {
                i++;
                int temp = arr[i];
                arr[i] = arr[j];
                arr[j] = temp;
            }
        }
        int temp = arr[i + 1];
        arr[i + 1] = arr[high];
        arr[high] = temp;
        return i + 1;
    }
    void sort(int arr[], int low, int high) {
        if (low < high) {
            int pi = partition(arr, low, high);
            sort(arr, low, pi - 1);
            sort(arr, pi + 1, high);
        }
    }
    public static void main(String args[]) {
        int arr[] = {10, 7, 8, 9, 1, 5};
        int n = arr.length;
        QuickSort qs = new QuickSort();
        qs.sort(arr, 0, n - 1);
        System.out.println("Sorted array: ");
        for (int i = 0; i < n; i++)
            System.out.print(arr[i] + " ");
    }
}