Question

c语言 求1！+2！+3！+...+n!的值.n由键盘输入

Answer 1

简单而高效！n的值不能超过13，否则会因为数据溢出而导致结果错误。

#include <stdio.h>

int main()
{
long i,n,m,sum=0;

scanf("%d",&n);
for(i=m=1;i<=n;i++)
{
m*=i;
sum+=m;
}
printf("%d\n",sum);
return 0;
}

Answer 2

#include "stdio.h"

int calc(int n)
{
if(n == 1)
return 1;
return n + calc(n-1);
}
int fun(int n)
{
int temp = 0;
for(int i=1;i<=n;++i)
{
temp += calc(i);
}
return temp;
}
void main()
{
int n=0;
printf("input n:\n");
scanf("%d",&n);
n = fun(n);
printf("result is :%d",n);
}

Answer 3

int i,j,sum;
for(i=1;i<n+1;i++)
{
for(j=1;j<i+1;j++)
sum+=j;
}

sum就是最后要求的值

Answer 4

#include <stdio.h>

int func(int n)
{
if(n==1)
return 1;
else
return n*func(n-1);
}

int main()
{
int i,n,sum=0;
scanf("%d",&n);
for(i=1;i<=n;i++)
sum+=func(i);
printf("%d\n",sum);

return 0;
}

Answer 5

#include "stdio.h"
#include <conio.h>
int main(){
int multi(int a);
int i,sum = 0,num;
printf("Please input a number:");
scanf("%d", &num);
for(i = 0; i < num; i ++){
sum += multi(i+1);
}
printf("Sum is %d", sum);
getch();
return 0;
}
int multi(int a){
if(a < 0){
printf("Unexpected error!");
}else if(1 == a){
return 1;
}else return a*multi(a - 1);
}