leetcode_plus_one

class Solution {
public:
    vector<int> plusOne(vector<int>& digits) {
        auto r_it = digits.rbegin();
        int add_number = 1;
        for(; r_it != digits.rend(); r_it++)
        {
            int sum = add_number + *r_it;
            if(sum/10 == 1)
            {
                add_number = 1;
                sum = sum % 10;
                *r_it = sum;
            }
            else
            {
                add_number = 0;
                *r_it = sum;
                break;
            }
        }
        if(add_number == 1)
        {
            digits.insert(digits.begin(),1);
        }
        return digits;
    }
};