求Sn=a+aa+aaa+...+aa...a的值

#include<cstdio> #include<algorithm> #include<iostream> #include<cmath> #include<iomanip> #include<cstring> using namespace std; int main() { int a,n,s=0,sum=0; cin >> a >> n; for(int i=1; i<=n; i++){ s+=a; a=a*10; sum+=s; } cout << sum << endl; return 0; }