题解 | #输出第5行的内容#

#include <iostream>

using namespace std;

long long factorial(int n);

int main()
{
    int n;
    cin >> n;
    long long  a;
    a = factorial(n);
    cout << a << endl;
}

long long factorial(int n)
{
    if (n == 1||n==0)
    {
        return 1;
    }
    else
    {
        return factorial(n - 1) * n;
    }
}