How to implement quick sort on python? - python-3.x

Question

maybe I’m the next person who asks how to release quick sort on python correctly. But it’s important for me to know if I wrote this algorithm correctly by reading the pseudocode from the textbook Essential Algorithms: A Practical Approach to Computer Algorithms.
When I run the code, I get this message. RecursionError: maximum recursion depth exceeded in comparison
import random
def quickSort(arr, start, end):
if start >= end: # if len(arr) < 2
return arr
else:
divideIndex = partition(arr, start, end)
quickSort(arr, start, divideIndex - 1)
quickSort(arr, divideIndex, end)
def partition(arr, head, tail):
left = head
right = tail
pivot = arr[(head + tail) // 2] # mid
while right >= left:
# looking through the array from the left
while arr[left] <= pivot:
left = left + 1
# looking through the array from the right
while arr[right] > pivot:
right = right - 1
# found a couple of elements that can be exchanged.
if left <= right:
swap(arr[right], arr[left])
# move the left and right wall
left = left + 1
right = right - 1
# return one elements if not found a couple
return left
def swap(arr1, arr2):
temp = arr1
arr1 = arr2
arr2 = temp
# Generator random variables
deck = list(range(50))
random.shuffle(deck)
start = 0
end = len(deck) - 1
print(quickSort(deck, start, end))

Answer 1

Try this:
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 quickSort(arr,low,high):
if low < high:
pi = partition(arr,low,high)
quickSort(arr, low, pi-1)
quickSort(arr, pi+1, high)