Add Binary <leetcode>

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

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

算法：模拟加法过程

 class Solution {
 public:
     string addBinary(string a, string b) {
         int  len1=a.size();
         int  len2=b.size();
         int c=;
         reverse(a.begin(),a.end());
         reverse(b.begin(),b.end());
         string s="";
         int len=max(len1,len2);
         for(int i=;i<len;i++)
         {
             int t=;
             if(i<len1)  t+=a[i]-'';
             if(i<len2)  t+=b[i]-'';
             t+=c;
             c=t/;
             s=(char)(t%+'')+s;
         }
         if(c>) s=(char)(c+'')+s;
         return s;
     }
 };