考虑使用map维护每个数出现的次数,发现可以顺便维护下map中最大的值 maxn ,答案就是 min(maxn + 1, n)

#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N = 2e5 + 5;
int __t = 1, n, x;
void solve() {
    map<int, int> mp;
    cin >> n;
    int maxn = 0;
    for (int i = 1; i <= n; i++) {
        cin >> x;
        mp[x]++;
        maxn = max(maxn, mp[x]);
    }
    cout << min(maxn + 1, n) << '\n';
    return;
}
int32_t main() {
#ifdef ONLINE_JUDGE
    ios::sync_with_stdio(false);
    cin.tie(0);
#endif
    // cin >> __t;
    while (__t--)
        solve();
    return 0;
}