第十二周项目三（2）：写出1*3*...n的阶乘

#include <iostream>using namespace std;long fid(int n);int main(){    int n;    cout<<"n=";    cin>>n;    if(n%2==0) cout<<"请输入奇数!"<<endl;    else cout<<"1*3*....*n="<<fid(n)<<endl;    return 0;}long fid(int n){    int a;    if(n==1)a=1;    else        a=n*fid(n-2);    return a;}