# coding=utf-8
def partition(arr, low, high):
    i = (low - 1)
    pivot = arr[high]
    for j in range(low, high):
        if arr[j] <= pivot:
            i = i + 1
            arr[i], arr[j] = arr[j], arr[i]

    arr[i + 1], arr[high] = arr[high], arr[i + 1]
    return i + 1


def recursion(arr, low, high):
    if low < high:
        pi = partition(arr, low, high)
        recursion(arr, low, pi - 1)
        recursion(arr, pi + 1, high)


def quicksort(arr, start=0, end=0):
    if end != 0:
        recursion(arr, start, end)
    else:
        recursion(arr, start, len(arr) - 1)