This solution works

static List<Integer> freqQuery(List<int[]> queries) {
    final Map<Integer, Integer> valueToFreq = new HashMap<>();
    final Map<Integer, Integer> freqToOccurrence = new HashMap<>();
    final List<Integer> frequencies = new ArrayList<>();

    int key;
    int value;
    Integer oldFreq;
    Integer newFreq;
    Integer oldOccurrence;
    Integer newOccurrence;
    for (int[] query : queries) {
        key = query[0];
        value = query[1];
        if (key == 3) {
            if (value == 0) {
                frequencies.add(1);
            }
            frequencies.add(freqToOccurrence.get(value) == null ? 0 : 1);
        } else {
            oldFreq = valueToFreq.get(value);
            oldFreq = oldFreq == null ? 0 : oldFreq;
            oldOccurrence = freqToOccurrence.get(oldFreq);
            oldOccurrence = oldOccurrence == null ? 0 : oldOccurrence;

            if (key == 1) {
                newFreq = oldFreq + 1;
            } else {
                newFreq = oldFreq - 1;
            }
            newOccurrence = freqToOccurrence.get(newFreq);
            newOccurrence = newOccurrence == null ? 0 : newOccurrence;

            if (newFreq < 1) {
                valueToFreq.remove(value);
            } else {
                valueToFreq.put(value, newFreq);
            }

            if ((oldOccurrence - 1) < 1) {
                freqToOccurrence.remove(oldFreq);
            } else {
                freqToOccurrence.put(oldFreq, oldOccurrence - 1);
            }
            freqToOccurrence.put(newFreq, newOccurrence + 1);
        }
    }
    return frequencies;
}