我怀疑，数据可能太极端了，缺乏中间数据。

我写了这样一个会 TLE 的错解，过了：

#include <cmath>
#include <iostream>

using namespace std;

int main()
{
    int num = 0, factor1 = 0, factor2 = 0;
    cin >> num;
    factor1 = num / 2;
    factor2 = ceil(sqrt(num));
    do
    {
        if (num % factor1 == 0)
        {
            cout << factor1 << endl;
            break;
        }
        else if (num % factor2 == 0)
        {
            cout << factor2 << endl;
            break;
        }
        --factor1;
        ++factor2;
    } while (factor1 >= 2 && factor2 < num);
    return 0;
}