Quick Sort

def quickSort(alist, lo, hi):

    if lo < hi:
        p = partition(alist, lo, hi)
        quickSort(alist, lo, p-1)
        quickSort(alist, p+1, hi)

    return alist

def partition(alist, lo, hi):

    p = alist[lo]
    L = lo + 1
    R = hi
    while True:
        while L <= R and alist[L] <= p:
            L += 1
        while L <= R and alist[R] >= p:
            R -= 1
        
        if R < L:
            alist[lo], alist[R] = alist[R], alist[lo]
            return R
        else:
            alist[L], alist[R] = alist[R], alist[L]

if __name__ = '__main__':
    uL = [54, 26, 93, 17, 77, 31, 44, 55, 20]
    sL = quickSort(uL[:], 0, len(uL) - 1)
    print(uL)
    print(sL)