program to add two binary numbers
class Solution {
public String addBinary(String a, String b) {
int i=a.length()-1;
int carry=0;
int j=b.length()-1;
int sum=0;
StringBuilder sb=new StringBuilder();
while(i>=0 || j>=0){
sum=carry;
if(i>=0){
sum+=a.charAt(i)-'0';
}
if(j>=0){
sum+=b.charAt(j)-'0';
}
sb.append(sum%2);
carry=sum/2;
i--;
j--;
}
if(carry!=0){
sb.append(carry);
}
return sb.reverse().toString();
}
}