/*
Given a non-negative number represented as an array of digits, plus one to the number.
The digits are stored such that the most significant digit is at the head of the list.
*/




void plusone(vector<int> &digits)
{
    int n = digits.size();
    for (int i = n - 1; i >= 0; --i)
    {
        if (digits[i] == 9)
        {
            digits[i] = 0;
        }
        else
        {
            digits[i]++;
            return;
        }
    }
        digits[0] =1;
        digits.push_back(0);

}