66. Plus One

//This is a easy problem , but don't solve it by iterating forward in the vector as you might think that only the last digit wil be changed but that is wrong if you are dealing 
//with a number like 99, then we might end up changing all the digits of the vector so you never know how long can the carry +1 travel, so better reverse  the linked list
//and then perform the addition. Don't forget ot consider the case when one digit in the vector increases when lst digit is>10 like 99+1 gives 100 so vector size increases by 1.
class Solution {
public:
    vector<int> plusOne(vector<int>& digits) {
       reverse(digits.begin(),digits.end());
       vector<int>ans;
        int carry=1;
        int sum;
        for(auto it=digits.begin();it!=digits.end();it++)
        {
             sum=*it+carry;
            if(sum<10)
                carry=0;
            else
                carry=1;
            ans.push_back(sum%10);
        }
        if(sum>=10)
            ans.push_back(1);
        reverse(ans.begin(),ans.end());
        return ans;
    }
};