用C++编程求Sn，n个a

#include<iostream>
#include<cmath>
using namespace std;
int main() {
    int n,a,t=0,s=0;
    cout<<"输入a:";
    cin>>a;
    cout<<"输入n:";
    cin>>n;
    for(int i=0;i<n;i++){
        t=t*10+a;
        s+=t;
    }
    cout<<s;
    return 0;
}

#include <stdio.h>
int main()
{
    int a,n;
    long long d,sum;
    scanf("%d%d",&a,&n);
    d = a;
    sum = a;
    for(int i=2;i<=n;i++)
    {
        d = d*10 + a;
        sum += d;
    }
    printf("%lld",sum);
    return 0;
}