from collections import Counter
from collections import defaultdict
# dict have nice O(1) lookup time, defaultdict is even faster!

def rep1(elements):
    if len(elements) != 24:
        return False

    most_common = Counter(elements).most_common(1)[0] # find most common element
    return most_common[1] == 1  # returns if its repeated only one time


def rep2(elements):
    if len(elements) != 24:
        return False

    couter = {}  # element counter
    for el in elements:
        if not couter.get(el, False):
            # add element to register
            couter[el] = 1
        else:
            # element already registered
            return False
    return True  # no interrupt so everything is fine


def rep3(elements):
    if len(elements) != 24:
        return False

    # directory with default value of 0
    counter = defaultdict(int)

    for el in elements:
        counter[el] += 1  # increment by one element count

    highest = max(counter, key=counter.get)  # find keyword with highest number
    return counter[highest] == 1  # returns if highest number is repeated


def checker(f, good, bad):
    print('[{}]:'.format(f.__name__))
    print('\tfor good: {}'.format(f(good)))  # feeds f with bad input
    print('\tfor bad: {}\n'.format(f(bad)))  # feeds f wit good input

if __name__ == '__main__':
    good =  '1234567890qwertyuiopasdf'
    bad =   '1134567890qwertyuiopasdf'
    checker(rep1, good, bad)
    checker(rep2, good, bad)
    checker(rep3, good, bad)