Exercise 10-2 recursive factorial sum

exercises 10-2 Recursively sum factorials (15 branch )

This problem requires a simple function to calculate the factorial of non negative integers , And use this function to find 1!+2!+3!+...+n! Value .

Function interface definition ：

double fact( int n );
double factsum( int n );

function fact Should return n The factorial , It is suggested to use recursion to realize . function factsum Should return 1!+2!+...+n! Value . The problem is to ensure that the input and output are within the double precision range .

Sample referee test procedure ：

#include <stdio.h>

double fact( int n );
double factsum( int n );

int main()
{
    int n;

    scanf("%d",&n);
    printf("fact(%d) = %.0f\n", n, fact(n));
    printf("sum = %.0f\n", factsum(n));
        
    return 0;
}

/*  Your code will be embedded here  */

sample input 1：

10

sample output 1：

fact(10) = 3628800
sum = 4037913

sample input 2：

0

sample output 2：

fact(0) = 1
sum = 0

double fact( int n ){
    double f;
    if(n>1){
        f=n*fact(n-1);
    }else{
        f=1;
    }
    return f;
}
double factsum( int n ){
    double sum=0;
    for(int i=1;i<=n;i++){
        sum+=fact(i);
    }
    return sum;
}