Add Binary

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;
    }
};