要最简单最简单的程序语言。

Question

Answer 1

不考虑溢出

#include <iostream>
using namespace std;
int main(){
    int n,res = 0,a = 1,temp = 0;
    cin >> n;
    for(int i = 1;i <= n;i++){
        a *= i;
        temp += a;
        res += temp;
    }
    cout << res;
}