编写函数fun求sum=d+(d+dd)+(d+dd+ddd)+...+(n个d))急急急

#include "stdio.h"

long fun(int d,int n)

{

/**********Program********/ 

/**********  End  **********/

} 

main()

{ int d,n;

  long sum,fun(int d, int n);

  scanf("%d%d",&d,&n);

  sum=fun(d,n);

  printf("sum=%ld\n",sum);

}

#include "stdio.h"

long fun(int d, int n)
{
    int i;
    long dn, adn, sum;
    
    sum = adn = dn = d;

    for (i = 2; i <= n; ++i)
    {
        dn *= d;
        adn += dn;
        sum += adn;
    }
    
    return sum;
} 

int main()
{ 
    int d, n;
    long sum;

    scanf("%d%d", &d, &n);
    sum = fun(d, n);

    printf("sum = %ld\n", sum);

    return 0;
}

// Output
5 3                                                                                                                                                                                
sum = 190