PAT 天梯赛 L1-013. 计算阶乘和 【水】

题目链接

https://www.patest.cn/contests/gplt/L1-013

AC代码

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <deque>
#include <vector>
#include <queue>
#include <string>
#include <cstring>
#include <map>
#include <stack>
#include <set>
#include <cstdlib>
#include <ctype.h>
#include <numeric>
#include <sstream>
using namespace std;

typedef long long LL;
const double PI = 3.14159265358979323846264338327;
const double E = 2.718281828459;
const double eps = 1e-6;
const int MAXN = 0x3f3f3f3f;
const int MINN = 0xc0c0c0c0;
const int maxn = 1e5 + 5;
const int MOD = 1e9 + 7;
double fac(int x)
{
    double sum = 1;
    for (int i = 2; i <= x; i++)
        sum *= i;
    return sum;
}

int main()
{
    int n;
    cin >> n;
    long double sum = 0;
    for (int i = 1; i <= n; i++)
    {
        sum += fac(i);
    }
    printf("%.0Lf\n", sum);
}