leetcode #66 in cpp

Solution: 

1.start from the tail of the input, and keep adding 1 until we reach the head of the input or the digit + 1 is less than 10. 

2.check if the head >= 10. If so insert an extra 1 to the input.

Code:

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