样例

#include <iostream>
#include <vector>

using namespace std;
vector<int> C;

void add(auto A,auto B){
    int t = 0;
    for(int i  = 0;i<=A.size()||i<=B.size();i++)
    {
        C.push_back((A[i] + B[i] + t)%10);
        if((A[i] + B[i]+t)>=10) t = 1;
        else t =0;
    }
    //-0
    for(int i = C.size()-1;i > 0 && C[i] == 0;i--) C.pop_back();
}
int main(){
    string a,b;
    cin>>a>>b;
    vector<int> A,B;
    for(int i =a.size()-1;i>=0;i--) A.push_back(a[i]-'0');
    for(int i =b.size()-1;i>=0;i--) B.push_back(b[i]-'0');
    //cs
    // for(int i =A.size()-1;i>=0;i--) cout<<A[i]<<endl;
    add(A,B);
    for(int i =C.size()-1;i>=0;i--) cout<<C[i];
    return 0;

}