exercise12.py

from random import randrange

def quick_sort(array):
    def partition(array, start, finish):
        pivot = array[start]

        less = [elem for elem in array[start+1:finish+1] if elem < pivot]
        greaterequal = [elem for elem in array[start+1:finish + 1] if elem >= pivot]
        new_array = less + [pivot] + greaterequal

        for i in range(start, finish+1):
            array[i]=new_array.pop(0)

        return start + len(less)

    def quick_sort_rec(array, start, finish):
        if start < finish:
            pos = partition(array,start,finish)
            quick_sort_rec(array,start,pos-1)
            quick_sort_rec(array,pos+1,finish)

    quick_sort_rec(array,0,len(array)-1)

ar = [randrange(100) for _ in range(20)]
print(ar)
quick_sort(ar)
print(ar)