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(); } }