iterative_merge_sort.py

from math import ceil
from random import randint

def mergesort(A):
    B = [None] * len(A)
    chunk_size = 1
    while chunk_size < len(A):
        for i in range(ceil(len(A) / chunk_size / 2)):
            merge(A, B, 
                start1 = 2 * i * chunk_size, 
                start2 = min((2 * i + 1) * chunk_size, len(A)), 
                end = min((2 * i + 2) * chunk_size, len(A)))
        A[:] = B
        chunk_size *= 2

def merge(src, dst, start1, start2, end):
    i = start1
    j = start2
    for index in range(start1, end):
        if j == end:
            dst[index] = src[i]
            i += 1
        elif i == start2:
            dst[index] = src[j]
            j += 1
        elif src[i] <= src[j]:
            dst[index] = src[i]
            i += 1
        else:
            dst[index] = src[j]
            j += 1
        
array = list(map(int, input().split()))
mergesort(array)
print(array)

def get_random_numbers(n):
    return [randint(0, 50) for _ in range(n)]

# for _ in range(10):
#     array = get_random_numbers(30)
#     mergesort(array)
#     print(array)