题解 | #牛群的编码#

import java.util.*;


public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param a string字符串
     * @param b string字符串
     * @return string字符串
     */
    public String addBinary (String a, String b) {
        // write code here
        int i = a.length() - 1;
        int j = b.length() - 1;
        int flag = 0;
        StringBuilder sb = new StringBuilder();
        while (i >= 0 || j >= 0||flag>0) {
            int sum=flag;
            if(i>=0){
                sum=sum+a.charAt(i)-'0';
                i--;
            }
            if(j>=0){
                sum=sum+(int)b.charAt(j)-'0';
                j--;
            }
            sb.insert(0,sum%2);
            flag=sum/2;
        }return sb.toString();
        }
        }