题解 | 函数实现计算一个数的阶乘

#include <iostream>
using namespace std;

long long factorial(int n);

int main() 
{

    int n;
    cin >> n;

    cout << factorial(n) << endl;

    return 0;
}

long long factorial(int n) {

    // write your code here......
    long long num=1;//注意定义long long
    while(n)
    {
        num*=n;
        n-=1;
    }
    return num;
}