Text-Based Mario Kart Racing Simulation

cout << endl << "Interval " << intervalCount << endl << endl;

    while(!mariokart.isEmpty()){
        cin >> checker; //Wiping "END" and updating input with a racer name, as we start the interval  

        while(checker != "DONE"){
            string racerName = checker; //Storing the original value read in
            for(int i = 0; i < checker.size(); i++){
                checker[i] = toupper(checker[i]); //Making the racer name capitalized, as it is the key to all map checks
            }
            //Checking if we update the racer or not: Using an unordered map, with keys as racername all capitalized, and boolean values
            auto racerUpdateIterator = racerUpdateCheck2.find(checker);
            if(racerUpdateIterator->second == true){ //
                cout << "Already updated " << racerName << " in this interval!" << endl << endl; //Due to formatting, already updated comes first
            } 
            else if(racerFinished.find(checker)->second != 0){
                cout << "Racer has already finished the race!" << endl << endl; //If hasn't been updated, then check if the user finished the race
            }
            else{  //Otherwise...update the value
                cin >> racingUnit; //Read in the next value as a double, the new distance away from finish line
                totalRacerCheck.find(checker)->second = true;
                racerUpdateCheck2.find(checker)->second = true;
                cout << "Updating " << racerName << endl;
                //Update value
                mariokart.decrease_priority(racerNames[checker], racingUnit); //Updating my priority queue of racers
                if(racingUnit <= 0){
                    racerFinished[checker] = racerPosition; //Assign racerPosition to racer that finished 

                    //Erasing from my totalRacerCheck if we go below value 0. This is to prevent continously checking
                    //for values that already finished
                    for(auto i = totalRacerCheck.begin(); i != totalRacerCheck.end(); i++){
                        if(i->first == checker){
                            totalRacerCheck.erase(i);
                            break;
                        }
                    }
                }
            }