输入一个正整数，计算1！+2！+n！

请问您需要什么语言的代码呢？以下为Python、Java和C++的代码：

Python代码：

n = int(input("请输入一个正整数："))
factorial = 1
sum = 0
for i in range(1, n+1):
factorial *= i
sum += factorial
print("1! + 2! + ... + n! =", sum)

Java代码：

import java.util.Scanner;

public class Main {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.print("请输入一个正整数：");
int n = input.nextInt();
int factorial = 1;
int sum = 0;
for (int i = 1; i <= n; i++) {
factorial *= i;
sum += factorial;
}
System.out.println("1! + 2! + ... + n! = " + sum);
}
}

C++代码：

#include <iostream>
using namespace std;

int main() {
int n, factorial = 1, sum = 0;
cout << "请输入一个正整数：" << endl;
cin >> n;
for (int i = 1; i <= n; i++) {
factorial *= i;
sum += factorial;
}
cout << "1! + 2! + ... + n! = " << sum << endl;
return 0;
}