import random
from string import digits
import time


def gen_sub_set(length, count):
    return {''.join((random.choice(digits) for x in range(length))) for x in range(count)}


def gen_rand_unique_digits(count=200000, length=6):
    result_set = set()
    while len(result_set) < count:
        new_len = count - len(result_set)
        result_set.update(gen_sub_set(length, new_len))
    return result_set

if __name__ == '__main__':

    t0 = time.time()
    for x in range(10):
        gen_rand_unique_digits()
    t1 = time.time()

    print('\nRuntime SET:  {0:.2f} Seconds'.format(t1 - t0))