题解 | #大整数的因子# 与进制转换思想类似

#include <iostream>
using namespace std;

string s;

int div(string c, int x)
{
    int remain = 0;
    for(int i = 0; i < c.size(); i++)
    {
        int k = remain * 10 + c[i] - '0';
        c[i] = k / x + '0';
        remain = k % x;
    }
    if(remain) return remain;
    return 0;
}

int main() {
    while(cin >> s)
    {
        if(s == "-1") break;
        int sum = 0;
        for(int i = 2; i < 10; i++)
        {
            if(div(s, i) == 0)
            {
                printf("%d ", i);
                sum++;
            }
        }
        if(!sum) printf("none\n");
        else printf("\n");
    }
}