第1个回答 2016-11-01
#include "stdio.h"
int myfact(int n){
if(n==1 || n==0)
return 1;
return n*myfact(n-1);
}
int main(void){
int i,n,s;
printf("Input n(int 0<=n<7)...\nn=");
if(scanf("%d",&n)!=1 || n<0 || n>6){
printf("Input error, exit...\n");
return 0;
}
for(n<<=1,s=i=0;i<=n;s+=myfact(i),i+=2);
printf("The result is %d\n",s);
return 0;
}