leetcode-67. Add Binary(二进制串求和)

https://leetcode.com/problems/add-binary/#/description

问题描述：

Given two binary strings, return their sum (also a binary string).For example,a = "11"b = "1"Return "100".

代码如下：

public class Solution {    public String addBinary(String a, String b) {        int i=a.length()-1;        int j=b.length()-1;        int carry=0;        StringBuilder sb=new StringBuilder();        while(i>=0 || j>=0)        {            int sum=carry;            if(i>=0) sum+=a.charAt(i--)-'0';            if(j>=0) sum+=b.charAt(j--)-'0';            sb.append(sum%2);            carry=sum/2;        }        if(carry!=0)sb.append(carry);        return sb.reverse().toString();    }}