set 去重

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 1e6 + 10, INF = 0x3f3f3f3f, MOD = 1E9 + 7;

void solve() {
    int n;
    cin >> n, getchar();
    string s;
    set<char> se;
    for (int i = 0; i < n; i++) {
        getline(cin, s);
        if (s[2] == 'A')
            se.insert(s[0]);
    }
    cout << se.sizer() << endl;
}
int main(int argc, char* argv[]) {
    int T;
    cin >> T;
    while (T--) {
        solve();
    }
    return 0;
}

map 去重

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 1e6 + 10, INF = 0x3f3f3f3f, MOD = 1E9 + 7;

void solve() {
    int n;
    cin >> n, getchar();
    string s;
    map<char, int> mp;
    for (int i = 0; i < n; i++) {
        getline(cin, s);
        if (s[2] == 'A')
            mp[s[0]] = 1;
    }
    cout << mp.size() << endl;
}
int main(int argc, char* argv[]) {
    int T;
    cin >> T;
    while (T--) {
        solve();
    }
    return 0;
}