【題解】ZeroJudge d194: 11572 – Unique Snowflakes

#include <iostream>
#include <set>
#include <queue>
using namespace std;

int t, n, a, ans;
set <int> st;
queue <int> q;

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cin >> t;
    while (t--){
        cin >> n;
        ans = 0;
        st.clear();
        while (n--){
            cin >> a;
            if (st.count(a)){
                ans = max(ans, (int)st.size());
                while (q.front()!=a){
                    st.erase(q.front());
                    q.pop();
                }
                q.pop();
            }
            st.insert(a);
            q.push(a);
        }
        ans = max(ans, (int)st.size());
        while (!q.empty()) q.pop();
        cout << ans << "\n";
    }
}