leetcode_question_66 Plus One

vector<int> plusOne(vector<int> &digits) {
// Start typing your C/C++ solution below
// DO NOT write int main() function
int length = digits.size();
if(length==0)
return digits;
bool carry = true;
int index = length-1;
while(carry && index >= 0)
{
digits[index] += carry;
if(digits[index] > 9)
{digits[index] = 0;carry = true;index--;}
else
{carry = false; break;}
};
if(carry)
digits.insert(digits.begin(), 1);
return digits;
}