实现n！+（n-1)!+...+1!

首先，设定变量

int p = 1;
int i = 0;
int sum = 0;
int x = 0;

其次，设计阶乘的函数

int jc(int p, int i)
{
for (; i != 1; i -= 1)
p *= i;
return p;
};

最后，设计主函数

int main()
{
printf("求解n!+(n-1)!+...+1!");
printf("请输入n");
scanf_s("%d", &i);\\输入i
for (; i!= 0; i--)\\循环若干次。将值都加给sum
  {
x = jc(p, i);\\求解单个数的阶乘
sum += x;\\求和
  }
printf("%d", sum);
}

成品：

int jc(int p, int i)
{
for (; i != 1; i -= 1)
p *= i;
return p;
};
int p = 1;
int i = 0;
int sum = 0;
int x = 0;
int main()
{
/*printf（"n");*/
printf("请输入n");
scanf_s("%d", &i);
for (; i!= 0; i--)
  {
x = jc(p, i);
sum += x;
  }
printf("%d", sum);
}