Osajono

input/code.cpp: In function 'void solve(int, std::string, int)':
input/code.cpp:38:46: warning: NULL used in arithmetic [-Wpointer-arith]
   if (a.at(i) != a.at(i - 1) && a.at(i-1) != NULL)
                                              ^

#include <iostream>
#include <algorithm>
#include <string>

using namespace std;

void solve(int paikka, string a, int lkm)
{
	int s = 0;
	char kirjain = a.at(paikka);

	int i = paikka;

	while (a.at(i) == kirjain)
	{
		s += 1;
		//cout << "s on: " << s << '\n';
		if (i == (int)a.size()-1)
		{
			//cout << "break" << '\n';
			break;
		}
		else
		{
			//cout << "While kierros loppuu" << '\n';
			i++;
		}
	}
	//cout << "Alkupaikka: " << paikka << "\n";
	
	//cout << "s on: " << s << '\n';
	lkm += (s*(1 + s) / 2);
	//cout << "nykyinen vastaus: " << lkm << '\n';

	//cout << "i: " << i << "\n";
	if (i == (int)a.size() - 1)
	{
		if (a.at(i) != a.at(i - 1) && a.at(i-1) != NULL)
			lkm += 1;
		cout << lkm << '\n';
	}
	else
	{
		//cout << "uusi kierros" << '\n';
		solve(i, a, lkm);
	}

}

int main() {
	ios_base::sync_with_stdio(0);

	string a;
	getline(cin, a);
	//int koko = a.size();

	sort(a.begin(), a.end());
	//cout << "uusi world order: " << a << '\n';

	solve(0, a, 0);
}

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: WRONG ANSWER

Test 12

Group: 3

Verdict: ACCEPTED

Test 13

Group: 3

Verdict: WRONG ANSWER

Test 14

Group: 3

Verdict: WRONG ANSWER

Test 15

Group: 3

Verdict: WRONG ANSWER