[NOIP1998 普及组] 阶乘之和 看一下哪里错了

Question

#include <bits/stdc++.h>
using namespace std;
int main()
{
    long long n, x = 1, a = 1, s = 0;
    cin >> n;
    for (int i = 1; i <= n; i++) {
        while (x <= i) {
            a = a * x;
            x++;
        }
        s = s + a;
    }
    cout << s;
    return 0;
}

Answer 1

题目链接：

[NOIP1998 普及组] 阶乘之和 - 洛谷 https://www.luogu.com.cn/problem/P1009