QuickSort

public class QuickSort{
      private void quickSort(int[] array, int startIndex, int endIndex) {
        if (startIndex >= endIndex) {
            return;
        }
        int p = part(array, startIndex, endIndex);
        quickSort(array, startIndex, p-1);
        quickSort(array, p + 1, endIndex);
    }

    private int part(int[] array, int startIndex, int endIndex) {
        int piv = array[startIndex];
        int left = startIndex;
        int right = endIndex;
        while (left != right) {
            while (left < right && array[right] > piv) {
                right--;
            }
            while (left < right && array[left] <= piv) {
                left++;
            }
            if (left < right) {
                int p = array[left];
                array[left] = array[right];
                array[right] = p;
            }
        }
        array[startIndex] = array[left];
        array[left] = piv;
        return left;
    }
}