Osajono

import java.util.*;
 
 
public class Tehtava1 {
	
	private static String aakkoset = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
	private static Random r;
		
 
	public static long osaJonot(String sana) {
		long maara = 0;
		HashSet<Character> kaydytKirjaimet = new HashSet<Character>();
		for (int i = 0; i<sana.length(); i++) {
			Character kirjain = sana.charAt(i);
			if (kaydytKirjaimet.contains(kirjain))
				continue;
			kaydytKirjaimet.add(kirjain);
			
			long maara2 = 0;
			
			for (int j = 0; j<sana.length(); j++) {
				//System.out.println(kirjain + ":" + sana.charAt(j));
				
				if (sana.charAt(j) == kirjain) {
					//System.out.println("loytyi");
					maara2++;
					maara += maara2;
					
				}
			}
		}
		
		return maara;
	}
	
	public static void main(String[] args) {
		
		r = new Random();
		//String sana = luoJono(10000);
		//sana = "ABAA";
		
		Scanner s = new Scanner(System.in);
		String sana = s.nextLine();
		
		
	
		System.out.println(osaJonot(sana));
		
	}
	
	
	
	public static String luoJono(int pituus) {
		StringBuilder sb = new StringBuilder();
		for (int i = 0; i<pituus; i++) {
			sb.append(aakkoset.charAt(r.nextInt(aakkoset.length())));
		}
		
		return sb.toString();
	}
 
}

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