OJ 若干大数相加

// we have defined the necessary header files here for this problem.
// If additional header files are needed in your program, please import here.

#include<iostream>
#include<cstring>
#include<vector>
#include<algorithm>
#include<cmath>
using namespace std;

//dp
int main()
{  
   int num1;
   cin>>num1;
    for(int k=0;k<num1;k++)
    {
        string a,b,sum;
        cin>>a>>b;
        string a1=a,b1=b;
       if(a.size()<b.size())
       {
           string temp=a;
           a=b;
           b=temp;
       }
       int len=a.size()-b.size();
       string c(len,'0');
       b=c+b;
       
       int carry=0; 
       for(int i=a.size()-1;i>=0;i--)
       {
           int num=(a[i]-'0')+(b[i]-'0')+carry;
           if(num>9)
           {
               sum.push_back((num-10)+'0');
               carry=1;
           }else
           {
               sum.push_back(num+'0');
               carry=0;
           }
           
       }
       if(carry!=0)
       sum.push_back(carry+'0');

       reverse(sum.begin(),sum.end());

      

        cout<<"Case "<<k+1<<":"<<endl;
        cout<<a1<<" + "<<b1<<" = "<<sum<<endl;
        cout<<endl;
        
    }
 
        
   return 0;
}