Osajono

import java.util.Scanner;

public class OsajonoTehtava {
    
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String input = scanner.nextLine();
     
        int[] numOfChars = new int[26];
        for (int i = 0; i < 26; i++) {
            numOfChars[i] = 0;
        }
        String alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        
        final int inputLength = input.length();
        for (int i = 0; i < inputLength; i++) {
            numOfChars[alphabet.indexOf(input.charAt(i))]++;
        }

        long result = 0;
        for (int i = 0; i < 26; i++) {
            result += ((long) numOfChars[i] * (numOfChars[i] + 1)) / 2;
        }
        
        System.out.println(result);
    }
}

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: ACCEPTED

Test 12

Group: 3

Verdict: ACCEPTED

Test 13

Group: 3

Verdict: ACCEPTED

Test 14

Group: 3

Verdict: ACCEPTED

Test 15

Group: 3

Verdict: ACCEPTED