public class QuickSort {

public static void quickSort(int[] arr) {

quickSort(arr, 0, arr.length-1);

}

public static void quickSort(int[] arr, int leftIndex, int rightIndex) {

int arrLength = rightIndex + 1 - leftIndex;

if (arrLength > 1) {

int partitionIndex = partition(arr, leftIndex, rightIndex);

quickSort(arr, leftIndex, partitionIndex-1);

quickSort(arr, partitionIndex+1, rightIndex);

}

}

public static int partition(int[] arr, int leftIndex, int rightIndex) {

int pivot = arr[rightIndex];

int partitionIndex = leftIndex;

for (int i = leftIndex; i < rightIndex; i++) {

if (arr[i] < pivot) {

swap(arr, i, partitionIndex);

partitionIndex++;

}

}

swap(arr, partitionIndex, rightIndex);

return partitionIndex;

}

public static void swap(int[] arr, int i, int j) {

int temp = arr[i];

arr[i] = arr[j];

arr[j] = temp;

}

}