[LeetCode] 67. Add Binary Java

题目：

Given two binary strings, return their sum (also a binary string).

For example,
a = "11"
b = "1"
Return "100".

题意及分析：求两个用字符串表示 的二进制数的和。主要是判断每次相加的和是否大于2，大于2便进1取余。

代码：

class Solution {
    public String addBinary(String a, String b) {
        String temp = "";
        int i = a.length()-1,j=b.length()-1;
        int count = 0;
        while(i>=0&& j>=0){
            count = count + (a.charAt(i)-'0') + (b.charAt(j)-'0');
            if(count > 1){
                temp = ((count)%2) + temp;
                count = 1;
            }else{
                temp = count + temp;
                count = 0;
            }
            i--;
            j--;
        }
        //a长一些
        while(i>=0){
            count += a.charAt(i)-'0';
            if(count > 1){
                temp = ((count)%2) + temp;
                count = 1;
            }else{
                temp = count + temp;
                count = 0;
            }
            i--;
        }
        //b长一些
        while(j>=0){
            count += b.charAt(j)-'0';
            if(count > 1){
                temp = ((count)%2) + temp;
                count = 1;
            }else{
                temp = count + temp;
                count = 0;
            }
            j--;
        }
        if(count == 1)
            temp = count + temp;
        return temp;
    }
}