public class Solution {
public String addBinary(String a, String b) {
if(a == null || a.isEmpty()) {
return b;
}
if(b == null || b.isEmpty()) {
return a;
}
char[] aArray = a.toCharArray();
char[] bArray = b.toCharArray();
StringBuilder stb = new StringBuilder();
int i = aArray.length - 1;
int j = bArray.length - 1;
int aByte;
int bByte;
int carry = 0;
int result;
while(i > -1 || j > -1 || carry == 1) {
aByte = (i > -1) ? Character.getNumericValue(aArray[i--]) : 0;
bByte = (j > -1) ? Character.getNumericValue(bArray[j--]) : 0;
result = aByte ^ bByte ^ carry;
carry = ((aByte + bByte + carry) >= 2) ? 1 : 0;
stb.append(result);
}
return stb.reverse().toString();
}
}
