quicksort implemented by python

>>> def partition(A,p,r):
    x = A[r]
    i = p-1
    for j in range(p,r):
        if A[j] <= x:
            i = i+1
            A[i],A[j]=A[j],A[i]
    A[i+1],A[r] = A[r],A[i+1]
    return i+1

def quicksort(A,p,r):
    if p < r:
        q = partition(A,p,r)
        quicksort(A,p,q-1)
        quicksort(A,q+1,r)

x = [1,4,8,2]
p = 0
r = len(x)-1
quicksort(x,p,r)
print x

def randompartition(A,p,r):
    import random
    i = random.randrange(p,r)
    A[p],A[r] = A[r],A[p]
    return partition(A,p,r)