Osajono

input/code.cpp: In function 'int main()':
input/code.cpp:29:7: warning: unused variable 'j' [-Wunused-variable]
   int j;
       ^
input/code.cpp:28:23: warning: ignoring return value of 'char* fgets(char*, int, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   fgets(s, 256, stdin);
                       ^

#include <stdio.h>
#include <iostream>
#include <string>
#include <string.h>
#include <stdlib.h>

#define A int('A')

using namespace std;

unsigned long calculate();
void calculateLetters(char s[256]);

struct Letters{
	int l[25];
};
Letters letters; 

int length;

int main(void){
	
	int i = 25;
	while(i--) letters.l[i] = 0;
	
	char s[256];
	while(true){
		fgets(s, 256, stdin);
		int j;
		if (s[length = strlen(s) - 1] == '\n'){
			s[length] = '\0';
			calculateLetters(s);
			break;
		}  length++;
		calculateLetters(s);
	}
	
	unsigned long sum = calculate();
	
	cout << sum;

	return 0;
	
}

void calculateLetters(char s[256]){
	unsigned int l = length;
	while(l--) letters.l[(s[l] - A)]++;
}

unsigned long calculate(){

	unsigned long sum = 0;
	unsigned long lsum;
	
	unsigned int l = length;
	
	while (l--){
		if (letters.l[l]){
			lsum = letters.l[l] + 1;
			lsum = ((lsum*lsum) - lsum) / 2;
			sum += lsum;
		}
	}
		
	return sum;
}

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