**Name**: Plus One**Difficulty**: Easy**Description**: Increment the large integer by one and return the resulting array of digits.

**Example**:

Input: digits = [4,3,2,1] Output: [4,3,2,2] Explanation: The array represents the integer 4321. Incrementing by one gives 4321 + 1 = 4322. Thus, the result should be [4,3,2,2].

Feels like I hacked this one, I also modified the vector in place which is probably not what was expected. Initially I was pushing the vector into a *unsigned long long*, adding one to it, then moving it back into a vector. But the test data included some very large numbers which caused runtime errors. In the end I used this caveman approach:

```
vector<int> plusOne(vector<int>& digits) {
if (digits.back() != 9) {
digits[digits.size() - 1] += 1;
return digits;
}
auto i = digits.end() - 1;
while (i > digits.begin() && *i == 9) {
*i = 0;
--i;
}
if (*i != 9) {
*i += 1;
return digits;
}
*i = 1;
digits.push_back(0);
return digits;
}
```