Submission

• Build index on the number of occurrences
• Otherwise, in linear query, one case will exceed the time limit

#include <bits/stdc++.h>

using namespace std;

string ltrim(const string &);
string rtrim(const string &);
vector<string> split(const string &);

// Complete the freqQuery function below.
vector<int> freqQuery(vector<vector<int>> queries) {
    map<int, int> m;
    map<int, int> c;
    vector<int> res;

    for(int i = 0; i < queries.size(); ++i) {
        if(queries[i][0] == 1) {
            auto it = m.find(queries[i][1]);
            if(it == m.end()){
                m.insert(make_pair(queries[i][1], 1));
                if(c.find(1) == c.end()) c.insert(make_pair(1, 1));
                else c[1]++;
            }
            else {
                c[it->second]--;
                if(c[it->second] == 0) c.erase(it->second);
                it->second++;
                if(c.find(it->second) == c.end()) c.insert(make_pair(it->second, 1));
                else c[it->second]++;
            }
        } else if (queries[i][0] == 2) {
            auto it = m.find(queries[i][1]);
            if(it != m.end()) {
                c[it->second]--;
                if(c[it->second] == 0) c.erase(it->second);
                it->second--;
                if(it->second == 0) m.erase(it);
                else c[it->second]++;
            }
        } else if (queries[i][0] == 3) {
            if(c.find(queries[i][1]) != c.end()) res.push_back(1);
            else res.push_back(0);
        }
    }
    return res;
}

int main()
{
    ofstream fout(getenv("OUTPUT_PATH"));

    string q_temp;
    getline(cin, q_temp);

    int q = stoi(ltrim(rtrim(q_temp)));

    vector<vector<int>> queries(q);

    for (int i = 0; i < q; i++) {
        queries[i].resize(2);

        string queries_row_temp_temp;
        getline(cin, queries_row_temp_temp);

        vector<string> queries_row_temp = split(rtrim(queries_row_temp_temp));

        for (int j = 0; j < 2; j++) {
            int queries_row_item = stoi(queries_row_temp[j]);

            queries[i][j] = queries_row_item;
        }
    }

    vector<int> ans = freqQuery(queries);

    for (int i = 0; i < ans.size(); i++) {
        fout << ans[i];

        if (i != ans.size() - 1) {
            fout << "\n";
        }
    }

    fout << "\n";

    fout.close();

    return 0;
}

string ltrim(const string &str) {
    string s(str);

    s.erase(
        s.begin(),
        find_if(s.begin(), s.end(), not1(ptr_fun<int, int>(isspace)))
    );

    return s;
}

string rtrim(const string &str) {
    string s(str);

    s.erase(
        find_if(s.rbegin(), s.rend(), not1(ptr_fun<int, int>(isspace))).base(),
        s.end()
    );

    return s;
}

vector<string> split(const string &str) {
    vector<string> tokens;

    string::size_type start = 0;
    string::size_type end = 0;

    while ((end = str.find(" ", start)) != string::npos) {
        tokens.push_back(str.substr(start, end - start));

        start = end + 1;
    }

    tokens.push_back(str.substr(start));

    return tokens;
}