题解 | #大整数的因子#

给大家一个完整的大数除法模板，而且返回了余数。

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

vector<int> div(vector<int> &A, int b, int &r)
{
    vector<int> C;
    r = 0;
    for (int i = A.size() - 1; i >= 0; --i)
    {
        r = r * 10 + A[i];
        C.push_back(r / b);
        r %= b;
    }

    reverse(C.begin(), C.end());
    while (C.size() > 1 && C.back() == 0)
        C.pop_back();
    return C;
}

int main()
{
    string c;
    while (cin >> c && c != "-1")
    {
        vector<int> a, ans;
        for (int i = c.size() - 1; i >= 0; --i)
            a.push_back(c[i] - '0');
        for (int i = 2; i <= 9; ++i)
        {
            int r = 0;
            auto res = div(a, i, r);
            if (r == 0)
                ans.push_back(i);
        }
         if (ans.empty())
             cout << "none";
         else
             for (int i = 0; i < ans.size(); ++i)
                 cout << ans[i] << " ";
        cout << endl;
    }
    return 0;
}