Given two binary strings a and b, return their sum as a binary string.
Example 1:
Input: a = "11", b = "1"
Output: "100"
Example 2:
Input: a = "1010", b = "1011"
Output: "10101"
Add binary digits from right to left with carry, just like decimal addition.
1class Solution {
2 public String addBinary(String a, String b) {
3 StringBuilder result = new StringBuilder();
4 int i = a.length() - 1, j = b.length() - 1;
5 int carry = 0;
6
7 while (i >= 0 || j >= 0 || carry > 0) {
8 int sum = carry;
9 if (i >= 0) sum += a.charAt(i--) - '0';
10 if (j >= 0) sum += b.charAt(j--) - '0';
11 result.append(sum % 2);
12 carry = sum / 2;
13 }
14
15 return result.reverse().toString();
16 }
17}