import unittest

def quick_sort(arr):

def _quick_sort(arr, first, last):

if first < last:

pivot = first

i = first

j = last

while i < j:

while arr[i] <= arr[pivot] and i < last:

i += 1

while arr[j] > arr[pivot]:

j -= 1

if i < j:

arr[i], arr[j] = arr[j], arr[i]

arr[pivot], arr[j] = arr[j], arr[pivot]

_quick_sort(arr, first, j - 1)

_quick_sort(arr, j + 1, last)

_quick_sort(arr, 0, len(arr) - 1)

return arr

class TestQuickSort(unittest.TestCase):

def test(self):

arr = quick_sort([5, 3, 2, 1, 4])

self.assertEqual(

arr,

[1, 2, 3, 4, 5]

)

arr = quick_sort([-1, -10, 2, 4, 1])

self.assertEqual(

arr,

[-10, -1, 1, 2, 4]

)

arr = quick_sort([1, -1, 5, 2, 4, 2])

self.assertEqual(

arr,

[-1, 1, 2, 2, 4, 5]

)

arr = quick_sort([5, 2])

self.assertEqual(

arr,

[2, 5]

)

arr = quick_sort([-1, -1, 2, 5, 4, 2])

self.assertEqual(

arr,

[-1, -1, 2, 2, 4, 5]

)

if __name__ == '__main__':

unittest.TestCase()