ModAdd

input/code.cpp: In function 'int main()':
input/code.cpp:13:7: warning: unused variable 'last' [-Wunused-variable]
   int last=1;
       ^~~~

#include<iostream>
#include<string>
#include<vector>

int main(){
  std::cin.tie(NULL);
  std::ios_base::sync_with_stdio(0);
  std::string a,b;
  std::cin>>a>>b;
  long long at_a,at_b;
  long long lena=a.length()-1;
  long long lenb=b.length()-1;
  int last=1;
  int ans;
  std::vector<long long> result;
  if(lena<lenb){
  for(long long i=0;i<lenb-lena;i++){
    std::cout<<b[i];
  }
  for(long long i=0;i<=lena;i++){
    long long ii=lena-i;
    at_a=a[lena-ii]-'0';
    at_b=b[lenb-ii]-'0';
    ans=(at_a+at_b)%10;
    //if(ans==0){
    //if(last==0){
    //std::cout<<std::endl;exit(0);}}last=ans;
    result.push_back(ans);
    
    
  }

  }
  else{
  for(long long i=0;i<lena-lenb;i++){
    std::cout<<a[i];
  }
  for(long long i=0;i<=lenb;i++){
    long long ii=lenb-i;
    at_a=a[lena-ii]-'0';
    at_b=b[lenb-ii]-'0';
    //std::cout<<"a "<<at_a<<" b "<<at_b;
    ans=(at_a+at_b)%10;
    result.push_back(ans);
    
  }

  }
  bool starting=1;
  for(auto u:result){
   if(u!=0){starting=0;}
    if(!starting){std::cout<<u;}
  }
  if(starting){std::cout<<"0";}std::cout<<"\n";
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED