Python Based Quickselect Implementation Resulting In Error

I have small python code that implements the quickselect discussed here. import random def Quickselect(A, k): if not A: return pivot = random.choice(A) i = 0

Solution 1:

Your error occurs because randrange breaks when the range is empty (i.e. randrange(1, 1)).

Use random.choice instead and change k <= len(A1) to k < len(A1):

def quick_select(A, k):
    pivot = random.choice(A)

    A1 = []
    A2 = []

    for i in A:
        if i < pivot:
            A1.append(i)
        elif i > pivot:
            A2.append(i)
        else:
            pass  # Do nothing

    if k <= len(A1):
        return Quickselect(A1, k)
    elif k > len(A) - len(A2):
        return Quickselect(A2, k - (len(A) - len(A2)))
    else:
        return pivot