FrequencyQueries.java

import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.function.*;
import java.util.regex.*;
import java.util.stream.*;
import static java.util.stream.Collectors.joining;
import static java.util.stream.Collectors.toList;

public class Solution {

    // Complete the freqQuery function below.


    public static void main(String[] args) throws IOException {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    BufferedWriter out = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));

    List<Integer> result = new ArrayList<>();
    int n = Integer.parseInt(in.readLine());
    HashMap<Long, Long> map = new HashMap<Long, Long>();
    HashMap<Long, Long> freq = new HashMap<Long, Long>();

    for (int i = 0; i < n; i++) {
        StringTokenizer s= new StringTokenizer(in.readLine());
        int a = Integer.parseInt(s.nextToken());
        final long b = Long.parseLong(s.nextToken());
        switch (a) {
            case 1:
                freq.computeIfPresent(map.get(b), (k, v) -> v == 1 ? freq.remove(map.get(b)) : v - 1);
                map.compute(b, (k, v) -> v == null ? 1 : v + 1);
                freq.compute(map.get(b), (k, v) -> v == null ? 1 : v + 1);
                break;
            case 2:
                freq.computeIfPresent(map.get(b), (k, v) -> v == 1 ? freq.remove(map.get(b)) : v - 1);
                map.computeIfPresent(b, (k, v) -> v == 1 ? map.remove(b) : v - 1);
                freq.compute(map.get(b), (k, v) -> v == null ? 1 : v + 1);
                break;
            case 3:
                result.add(freq.containsKey(b) ? 1 : 0);
                break;
        }
    }
    out.write(result.stream().map(Object::toString).collect(joining("\n")) + "\n");

    in.close();
    out.close();
}

}