题解 | #计算一个数的阶乘#

#include <iostream>
using namespace std;
long long calculateFactorial(int n) 
{
    if (n < 0 || n > 20) {
        return -1; // 输入了范围外的
    }
    long long result = 1;
    for (int i = 1; i <= n; ++i) 
    {
        result *= i;
    }
    return result;
}

int main() {
    int n;
    cin >> n;

    long long factorial = calculateFactorial(n);//调用函数

    if (factorial == -1) {
        cout << "输入不对" << endl;//范围外
    } 
    else {
        cout << factorial << endl;
    }

    return 0;
}