https://oj.leetcode.com/problems/add-binary/  
实”

1 public class Solution {

      public String addBinary(String a, String b) {

         char c1[]=a.toCharArray();

         char c2[]=b.toCharArray();

         int len1=a.length();

         int len2=b.length();

         int lo=len1;

         if(len1<=len2)

         {

             lo=len2;

         }

         int ans[]=new int[lo+1];

         int k=0;

         int ia=len1-1;

         int ib=len2-1;

         int  jinwei=0;

         while(ia>=0&&ib>=0)

         {

             ans[k]=c1[ia--]-'0'+c2[ib--]-'0'+jinwei;

             jinwei=ans[k]/2;

             ans[k]=ans[k]%2;

             k++;

         }

         while(ia>=0)

         {

             ans[k]=c1[ia--]-'0'+jinwei;

             jinwei=ans[k]/2;

             ans[k]=ans[k]%2;

             k++;

         }

         while(ib>=0)

         {

             ans[k]=c2[ib--]-'0'+jinwei;

             jinwei=ans[k]/2;

             ans[k]=ans[k]%2;

             k++;

         }

         StringBuffer sbf=new StringBuffer();

         if(jinwei==1) sbf.append(1);

        for(int j=lo-1;j>=0;j--)

        {

            sbf.append(ans[j]);

        }

        return sbf.toString();

     }

 }