Codeforces Round 917 (Div. 2) 1917B - Erase First or Second Letter Solution

 Problem Link :  https://codeforces.com/contest/1917/problem/B

Solution in C++:

1. /// Author : AH_Tonmoy
2. #include <bits/stdc++.h>
3. using namespace std;
4. int32_t main() {
5. ios_base::sync_with_stdio(0);
6. cin.tie(0);
7. int t;
8. cin >> t;
9. while (t--) {
10. int n ; cin >> n ;
11. string s ; cin >> s ;
12. set<char>st ;
13. long long ans = 0 ;
14. for (auto i : s){
15. st.insert(i) ;
16. ans += st.size() ;
17. }
18. cout << ans <<'\n';
19. }
20. return 0 ;
21. }