大整数的阶乘

#include <iostream>using namespace std;int main(){    int n;    while(cin >> n)    {        if(n == 0 || n == 1)            cout << 1 << endl;        else        {            int a[10000] = {0}, i, j, sum, t, k, q;            a[0] = 1;            k = 1;            for(i = 2; i <= n; i++)            {                sum = 0;                for(j = 0; j < k; j++)                {                    t = a[j] * i + sum;                    a[j] = t % 10;                    sum = t / 10;                }                while(sum)                {                    a[k++] = sum % 10;                    sum /= 10;                }            }            for(q = k - 1; q >= 0; q--)                cout << a[q];            cout << endl;        }    }    return 0;}