plus one.cpp

class Solution {
public:
    vector<int> plusOne(vector<int>& digits) {
        bool next_step = true;
        int pos = digits.size() - 1;
        
        while (next_step && (pos >= 0)) {
            digits[pos] += 1;
            if (digits[pos] == 10) {
                digits[pos] = 0;
                next_step = true;
            } else {
                next_step = false;
            }
            pos -= 1;
        }
        
        if (next_step) {
          digits.insert(digits.begin(), 1);
        }
        
        return digits;
    }
};