c#

        public static List<int> freqQuery(List<List<int>> queries)
        {
            Dictionary<long, int> res = new Dictionary<long, int>();
            List<int> ret = new List<int>();
            foreach (List<int> query in queries)
            {
                switch(query[0])
                {
                    case 1:
                        if (!res.ContainsKey(query[1]))
                        {
                            res.Add(query[1], 1);
                        } else
                        {
                            res[query[1]]++;
                        }

                        break;
                    case 2:
                        if (res.ContainsKey(query[1]))
                        {
                            if (res[query[1]] == 1)
                            {
                                res.Remove(query[1]);
                            }
                            else
                            {
                                res[query[1]]--;
                            }
                        }
                        break;
                    case 3:
                        int y = 0;
                        if (res.Values.Contains(query[1])) { y = 1; }
                        ret.Add(y);
                        break;
                }
            }

            return ret;

        }