1833A - Musical Puzzle - CodeForces Solution

#include <iostream>
#include <bits/stdc++.h>

using namespace std;

int main() {
    int t;
    cin>>t;
    while(t--){
        int n;
        cin>>n;
        set<string> se;
        string s;
        cin>>s;
        int cnt=0;
        for(int i=0; i<n-1; i++){
            string check="";
            check+=s[i];
            check+=s[i+1];
            se.insert(check);
        }
        cout<<se.size()<<endl;
    }

    return 0;
}