C语言编程：求1!+2!+3!+4!+5!+6!+7!+8!+9!(用for循环编写)

Question

很着急，谢谢

Answer 1

9*9!还在int型范围内，而题设和要比9*9!小很多，所以用int型变量就可以准确解决。用一个for循环兼作求阶乘和求和两项功能，空间、时效都较经济。举例代码如下：

#include "stdio.h"
int main(int argc,char *argv[]){
int s,i,t;
for(s=0,t=i=1;i<10;s+=t*=i++);
printf("1!+2!+3!+...+9! = %d\n",s);
return 0;
}

Answer 2

#include<stdio.h>
main()
{float i,s=0,t=1;<br/>for(i=1;i<=9;i++)<br/>{t*=i;s+=t;}
printf("%e",s);
}

Answer 3

#include<stdio.h>long fun(int i){long s = 1;if (i == 0)return s;else{for (int j = 1; j<=i; j++)s *= j;}return s;}int main(){long s = 1;int n;scanf("%d",&n);for (int i = 0; i<=n;i++)s += fun(i);printf("%d\n",s);return 0}