第二周任务2

#include <iostream>


long fac(int n);


double asd(int d, int f);


using namespace std;


int main()
{
int a,b;


cout << "请输入要求联合数的下标及上标：" << endl;


cin >> a >> b;


cout << "结果为：" << asd(a,b);


cout << endl;


return 0;
}


long fac(int n)
{
int sum = 1;


    for (; n > 1; n--)
{
sum = sum * n;

}