Osajono

#include <bits/stdc++.h>

#define i64 long long
#define u64 unsigned long long
#define i32 int
#define u32 unsigned int

#define pii pair<int, int>
#define pll pair<long long, long long>

#define defmod 1000000007
using namespace std;

int c[101010][26] = {0};
int main(){
	cin.sync_with_stdio(0);
	cin.tie(0);
	string s; cin >> s;
	int n = s.length();
	c[0][s[0]-'A']++;
	for(int i = 1; i < n; i++){
		for(int j = 0; j < 26; j++){
			c[i][j] = c[i-1][j];
		}
		c[i][s[i]-'A']++;
	}
	i64 re = 0;
	for(int i = 0; i < n; i++){
		re+=1+c[n-1][s[i]-'A']-c[i][s[i]-'A'];
	}
	cout << re << endl;
	return 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: 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