题目：

题解：

class Solution {public String addBinary(String a, String b) {StringBuffer ans = new StringBuffer();int n = Math.max(a.length(), b.length()), carry = 0;for (int i = 0; i < n; ++i) {carry += i < a.length() ? (a.charAt(a.length() - 1 - i) - '0') : 0;carry += i < b.length() ? (b.charAt(b.length() - 1 - i) - '0') : 0;ans.append((char) (carry % 2 + '0'));carry /= 2;}if (carry > 0) {ans.append('1');}ans.reverse();return ans.toString();}
}