class Main {
  public static void main(String[] args) {
    System.out.println("Hello world!");
    int[] arr = {4,2,3,10,23,1,43};
    sort1(arr);
    for (int i=0;i<arr.length;i++) {
      System.out.println(arr[i]);
    }
  }

  public static void sort1 (int[] arr) {
      if (arr == null || arr.length == 1) {
          return;
      }
      quickSort(arr, 0, arr.length -1);
  }


public static void quickSort(int[] arr, int left, int right) {
    if (left >= right) {
        return;
    }
    int pivot = arr[left];
    int i = left, j = right;
    while (i < j) {
        while (i < j && arr[j] >= pivot) {
            j--;
        }
        if (i < j) {
            arr[i++] = arr[j];
        }
        while (i < j && arr[i] < pivot) {
            i++;
        }
        if (i < j) {
            arr[j--] = arr[i];
        }
    }
    arr[i] = pivot;
    quickSort(arr, left, i - 1);
    quickSort(arr, i + 1, right);
}

}