import random

def merge_sort(A):

def merge_sort_recursive(A, p, r):

if p < r:

q = (p + r) // 2

merge_sort_recursive(A, p, q)

merge_sort_recursive(A, q + 1, r)

merge(A, p, q, r)

def merge(A, p, q, r):

L = A[p:q+1]

R = A[q+1:r+1]

i = j = 0

k = p

while i < len(L) and j < len(R):

if L[i] <= R[j]:

A[k] = L[i]

i += 1

else:

A[k] = R[j]

j += 1

k += 1

while i < len(L):

A[k] = L[i]

i += 1

k += 1

while j < len(R):

A[k] = R[j]

j += 1

k += 1

merge_sort_recursive(A, 0, len(A) - 1)

if __name__ == "__main__":

print("Now displaying MergeSort")

A = [random.randint(0, 1000) for _ in range(random.randint(5, 100))]

print("Before:", A)

merge_sort(A)

print("After:", A)