Use one Map for insertion and deletion of the value and another Map for the Frequency of the occurence.

vector freqQuery(vector> queries) { vector retVector; std::unordered_map elemValueMap; std::unordered_map freqMap; std::unordered_map::iterator elemValueMapIter; int nLoopCounter = 0; std::cout << queries.size() << std::endl; for (nLoopCounter = 0; nLoopCounter < queries.size(); nLoopCounter++) { vector tempVector = queries.at(nLoopCounter); int nValue = tempVector.at(1); switch (tempVector.at(0)) { case 1: // Remove 1 from the freqMap as the freq is moving to next freq if(freqMap[elemValueMap[nValue]]) freqMap[elemValueMap[nValue]]--; elemValueMap[nValue]++;

            // Add 1 to the freqMap for the new freq
            freqMap[elemValueMap[nValue]]++;
            break;

        case 2:
            if(elemValueMap.count(nValue)) {
                if(elemValueMap[nValue] > 0) {
                    // Remove 1 from the freqMap as the freq is moving to prev freq
                    if(freqMap[elemValueMap[nValue]] > 0)
                        freqMap[elemValueMap[nValue]]--;
                    elemValueMap[nValue]--;
                    // Add 1 to the freqMap for the old reduced freq
                    freqMap[elemValueMap[nValue]]++;
                }
            }
            break;

        case 3:
            int nFlag = (0 != freqMap[nValue]) ? 1 : 0;
            retVector.push_back(nFlag);
            break;
    }
}
return (retVector);

}