String Manipulation-Sherlock and the Valid String.py

#Problem Link : https://www.hackerrank.com/challenges/sherlock-and-valid-string/problem?isFullScreen=true&h_l=interview&playlist_slugs%5B%5D=interview-preparation-kit&playlist_slugs%5B%5D=strings

#Ans:

#!/bin/python3

import math
import os
import random
import re
import sys

#
# Complete the 'isValid' function below.
#
# The function is expected to return a STRING.
# The function accepts STRING s as parameter.
#

def count(s):
    frequencies = [0] * 26

    for letter in s:
        frequencies[ord(letter) - ord('a')] += 1

    return frequencies


def solve(s):
    frequencies = sorted(filter(lambda x: x > 0, count(s)))

    if len(set(frequencies)) > 2:
        return 'NO'

    if (frequencies[0] == frequencies[-1] or
            (frequencies[0] == 1 and frequencies[0] != frequencies[1]) or
            frequencies[1] - frequencies[0] == 1 or
            frequencies[-1] - frequencies[-2] == 1):
        return 'YES'

    return 'NO'


def main():
    s = input()
    print(solve(s))


if __name__ == '__main__':
    main()