超长正整数相加

#include<iostream>
#include<string>
#include<algorithm>
using namespace std;

int main()
{
    string s1,s2;
    int i,len1,len2,max;
    while(cin>>s1>>s2)
    {
        len1=s1.length();
        len2=s2.length();
        maxlen=len1>len2?len1:len2;
        reverse(s1.begin(),s1.end());
        reverse(s2.begin(),s2.end());
        int temp=0,k=0,j;
        int sum[512];
        for(i=0; i<maxlen; i++)
        {
            int a=0,b=0;
            if(i<len1)
                a=s1[i]-'0';
            else
                a=0;
            if(i<len2)
                b=s2[i]-'0';
            else
                b=0;
            int result=a+b+temp;
            temp=result>9?1:0;
            sum[k++]=result%10;
        }
        if(temp>0)
        {
            sum[k]=1;
            for(j=k; j>=0; j--)
                cout<<sum[j];
        }
        else
        {
            for(j=k-1; j>=0; j--)
                cout<<sum[j];
        }
        cout<<endl;
    }
    return 0;
}