class Solution {public:    string addBinary(string a, string b) {        string result;        reverse(a.begin(),a.end());        reverse(b.begin(),b.end());                int maxlength=max(a.size(),b.size());        int carry=0;                for(int i=0;i<maxlength;++i)        {            int ai=i<a.size() ? a[i]-‘0‘:0;            int bi=i<b.size() ? b[i]-‘0‘:0;                        int sum=ai+bi+carry;            result.insert(result.begin(),sum%2+‘0‘);            carry=sum/2;        }                if(carry==1)            result.insert(result.begin(),‘1‘);        return result;    }};