Add Binary Strings

//User function template for C++
class Solution{
public:	
	string addBinary(string A, string B)
	{
	    // your code here
	     string ans="";

     int carry=0;

     int i=A.size()-1,j=B.size()-1;

     while(i>=0 && j>=0){

         int t=A[i]-'0'+B[j]-'0'+carry;

         ans+=to_string(t%2);

         carry=t/2;

         i--;

         j--;

     }

     while(i>=0){

         int t=A[i]-'0'+carry;

         ans+=to_string(t%2);

         carry=t/2;

         i--;

     }

     while(j>=0){

         int t=B[j]-'0'+carry;

         ans+=to_string(t%2);

         carry=t/2;

         j--;

     }

     if(carry)

         ans+=to_string(carry);

     reverse(ans.begin(),ans.end());

     string res="";

     int idx=-1;

     for(int i=0;i<ans.length();i++){

         if(ans[i]!='0'){

             idx=i;

             break;

         }

     }

     for(int i=idx;i<ans.length();i++){

         res+=ans[i];

     }

     return res;
	}
};