Osajono

import math

def binomialCoefficient(n, k):
    if n < k:
        return 0
    return factorial(n) / (factorial(k) * (factorial(n - k)))
    
    
def factorial(n):
    if n == 0 or n == 1:
        return 1
        
    result = 1
    for i in range(2, n + 1):
        result *= i
        
    return result
    
input = input()
if len(input) == 0:
    print (0)
    sys.exit()

letterCounts = [0] * 26

for i in range(0, len(input)):
    letter = ord(input[i])
    letterCounts[letter - 65] += 1
 
subsets = 0
for i in range(0, 26):
    subsets += (binomialCoefficient(letterCounts[i], 2) + letterCounts[i])
    
print (math.floor(subsets))

Test 1

Group: 1

Verdict: ACCEPTED

Test 2

Group: 1

Verdict: ACCEPTED

Test 3

Group: 1

Verdict: ACCEPTED

Test 4

Group: 1

Verdict: ACCEPTED

Test 5

Group: 1

Verdict: ACCEPTED

Test 6

Group: 2

Verdict: ACCEPTED

Test 7

Group: 2

Verdict: ACCEPTED

Test 8

Group: 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: ACCEPTED

Test 10

Group: 2

Verdict: ACCEPTED

Test 11

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 12

Group: 3

Verdict: ACCEPTED

Test 13

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 14

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 15

Group: 3

Verdict: TIME LIMIT EXCEEDED