leetcode860

bool lemonadeChange(vector<int>& bills) {
    int FIVE = 0;
    int TEN = 0;
    int TWEN = 0;

    int N = bills.size();
    for (int i = 0; i < N; i++)
    {
        int p = bills[i];
        if (p == 5)
        {
            FIVE++;
        }
        else if (p == 10)
        {
            TEN++;
            FIVE--;
        }
        else if (p == 20)
        {
            TWEN++;
            if (TEN > 0)
            {
                TEN--;
                FIVE--;
            }
            else
            {
                FIVE -= 3;
            }
        }

        if (FIVE < 0 || TEN < 0 || TWEN < 0)
        {
            return false;
        }
    }
    return true;
}