Cacher is the code snippet organizer for pro developers

/**
 * Given two binary strings, return their sum (also a binary string).
 * For example,
 * a = "11"
 * b = "1"
 * Return "100".
 */
 
public class Solution {
    public String addBinary(String a, String b) {
        StringBuilder sb = new StringBuilder();
        int m = a.length() - 1, n = b.length() - 1, carry = 0;
        while(m >= 0 || n >= 0) {
            int sum = carry;
            if(m >= 0) sum += a.charAt(m--) - '0';
            if(n >= 0) sum += b.charAt(n--) - '0';
            sb.append (sum % 2);
            carry = sum / 2;
        }
        if(carry != 0) sb.append(carry);
        return sb.reverse().toString();
    }
}