LeetCode 题解之Add Binary

1、题目描述

2、题目分析

使用string 的逆向指针，做二进制加法，注意进位问题就可以。

3、代码

 string addBinary(string a, string b) {

         string::reverse_iterator it_a = a.rbegin() ;
         string::reverse_iterator it_b = b.rbegin() ;

         string s;
         string s0 = "";
         string s1 = "";
         int up = ;
         while( it_a != a.rend() && it_b != b.rend() ){
             if( *it_a - ''  + *it_b - ''  + up ==  ){
                 s = s1 + s;
                 up = ;
             }else if( *it_a - '' + *it_b - '' + up ==  ){
                 s = s0 + s;
                 up = ;
             }else if( *it_a - '' + *it_b - '' + up ==  ){
                 s = s0 + s;
                 up=;
             }else if( *it_a - '' + *it_b - '' + up ==  ){
                 s = s1 + s;
                 up = ;
             }
             ++it_a ;
             ++it_b ;
         }

         while( it_a != a.rend() ){
             if( *it_a - '' + up ==   ){
                 s = s0 + s;
                 up = ;
             }else if( *it_a - '' + up == ){
                 s = s1 + s;
                 up = ;
             }else{
                 s = s0 + s;
                 up = ;
             }
             ++it_a ;
         }

         while( it_b != b.rend() ){
             if( *it_b - '' + up ==  ){
                 s = s0 + s;
                 up = ;
             }else if(*it_b - '' + up == ){
                 s = s1 + s;
                 up =;
             }else{
                 s = s0 + s;
                 up = ;
             }
             ++it_b;
         }

         if( up ==  ){
             s = s1 + s;
         }

         return s;

     }