Osajono

#include <iostream>
#include <string>
#include <map>

using namespace std;

int main() {
	cin.sync_with_stdio(false);
	string chrw;
	cin >> chrw;

	int len = chrw.size();
	
	map<long long, long long> let;
	for (int i = 0; i < len; i++) {
		let[(long long)chrw[i]]++;
	}
	
	long long count = 0;
	for (auto const &cur : let) {
		count += (cur.second - 1)*cur.second / 2 + cur.second;
	}
	cout << count;
}

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