Jerry & The Gilmore Girls

bool tickets(const std::vector<int>& customers) {
    int fifties = 0, tf = 0; //tf = twentyfives
    for (int bill : customers) {
        if (bill == 25) { tf++; } //need 0 change
        else if (bill == 50) {
            if (--tf < 0) return false; //needs 25 change
            fifties++;
        }
        else { //bill == 100, needs (50+25) OR (25*3) change
            if (fifties > 0 && tf > 0) { fifties--; tf--; }
            else if ((tf -= 3) < 0) { return false; }
        }
    }
    return true;
}