请教一个简单c++问题不会啊

题目要求用循环

#include <iostream>
using namespace std;
int main()
{
    int n,t,sum = 0;
    int i = 1;
    cin >> n;
    //n翻转，比如n=123，翻转后n=321
    while(n)
    {
        t = n%10;
        sum = sum *10 + t;
        n/=10;
    }
    //cout << sum<<endl;

    n = sum;
    sum = 0;
    while(n)
    {
        t = n%10;
        sum += t*i;
        n/=10;
        i++;
    }

    cout << sum << endl;
    return 0;
}