输入整数n，编写程序求 1!+2!+3!+...+n! 的结果。

这道题可以使用循环来解决。下面是三种不同语言的代码实现：

C语言代码实现：

#include <stdio.h>
int main() {
    int n, i, j;
    double p = 1, sum = 0;
    printf("请输入一个整数：");
    scanf("%d", &n);
    for (i = 1; i <= n; i++) {
        p = 1;
        for (j = 1; j <= i; j++) {
            p = p * j;
        }
        sum = sum + p;
    }
    printf("1!+2!+...+%d!=%.0f\n", n, sum);
    return 0;
}

Java语言代码实现：

import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        int n = input.nextInt();
        double sum = 0;
        for (int i = 1; i <= n; i++) {
            double p = 1;
            for (int j = 1; j <= i; j++) {
                p = p * j;
            }
            sum = sum + p;
        }
        System.out.printf("%.0f", sum);
    }
}

Python语言代码实现：

n = int(input("请输入一个整数："))
sum = 0
for i in range(1, n+1):
    p = 1
    for j in range(1, i+1):
        p = p * j
    sum = sum + p
print(sum)