longest_duplicates.py

import random


NUMBER_OF_TESTCASES = 100
LETTERS = [chr(i) for i in range(97, 97+26)]  # all letters from 'a' to 'z'


def random_string_generator():
    string_blocks = random.randint(1, 100)
    string = ''
    for i in range(string_blocks):
        string += random.choice(LETTERS) * random.randint(1, 10)
    return string


# input string should consist of 1 char at least
def longest_duplicates_counter(string):
    max_number_of_duplicates = 1
    best_candidate = string[0]
    current_number_of_duplicates = 1
    current_candidate = string[0]

    for i in range(1, len(string)):
        if string[i] == current_candidate:
            current_number_of_duplicates += 1
            # if we need first best candidate - use >, if we need last - use >=
            if current_number_of_duplicates > max_number_of_duplicates:
                max_number_of_duplicates += 1
                best_candidate = current_candidate
        else:
            current_number_of_duplicates = 1
            current_candidate = string[i]

    print(f'String is: {string}')
    print(f'Character: {best_candidate}')
    print(f'Length of the sequence:: {max_number_of_duplicates}')


for case in range(NUMBER_OF_TESTCASES):
    longest_duplicates_counter(random_string_generator())