#include <iostream>
using namespace std;
int fib(int n);
int main(){
cout<<fib(20)<<endl; //输出
return 0;
}
//返回Fibnacci序列中的第n个数
int fib(int n)
{ int f;
if(n==0)
f=0;
else if(n==1)
f=1;
else
{
f=fib(n-1)+fib(n-2);
return f;
}
}
<img src="https://img-blog.youkuaiyun.com/20160320101806347?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQv/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center" alt="" />
\\